Computing device that can save memory by correcting bitmaps for images that overlap each other in an electronic document the operating method thereof

Abstract

The present invention provides a computing device and a method of operation that can save memory by correcting bitmaps of images overlapping each other on an electronic document, thereby supporting the saving of memory capacity used when an electronic document is displayed on the computing device.

Description

Technology Field

[0001] The present invention relates to a computing device capable of saving memory by correcting bitmaps of images overlapping each other on an electronic document, and a method of operating the same. Background Technology

[0002] Recently, with the widespread adoption of computing devices such as computers, smartphones, and tablet PCs, various types of electronic document programs are being released that enable users to view, create, and edit electronic documents using these devices.

[0003] These electronic document programs include word processors that support the creation and editing of basic documents, spreadsheets that assist with data input, formula calculations, and data management, and presentation programs that assist the presenter's presentation.

[0004] Users often insert images into documents when creating electronic documents. When such an electronic document with inserted images is opened on a computing device, if the computing device were to directly read the image from the document file stored on the device’s secondary storage device, such as the HDD (Hard Disk Drive) or SSD (Solid State Drive), and render it on the screen every time, the speed at which the image is displayed on the screen would be very slow. Therefore, the computing device creates a bitmap for the image, loads it onto the RAM (Random Access Memory) installed on the computing device, and then uses I / O (Input / Output) with the RAM to quickly read the image and render it on the screen.

[0005] As a result, when an electronic document containing multiple images is opened on a computing device, the amount of RAM used to render the electronic document increases, which may cause a problem where there is insufficient remaining RAM available for other applications.

[0006] Therefore, research on image processing techniques is necessary to efficiently use memory when rendering images inserted in electronic documents and displaying them on the screen.

[0007] In this regard, when multiple images are inserted overlapping each other in an electronic document as shown in FIG. 2, for the remaining images (212, 213) excluding the top image (211), since the overlapping part is not visible on the screen, there is no need to create a bitmap for the overlapping part and load it into RAM. Accordingly, when multiple images exist overlapping each other in an electronic document as shown in FIG. 2, for the images (212, 213) located at the bottom, instead of loading a bitmap corresponding to the entire image into RAM, a bitmap with the overlapping part excluded is created and loaded into RAM, thereby allowing for the introduction of a technique to minimize the memory usage required for image rendering. The problem to be solved

[0008] The present invention aims to support the saving of memory capacity when an electronic document is displayed on the computing device by presenting a computing device and a method of operation thereof that can save memory through the correction of bitmaps for images that overlap each other on an electronic document. means of solving the problem

[0009] A computing device capable of saving memory by correcting bitmaps for images overlapping each other on an electronic document according to an embodiment of the present invention comprises: a display unit that, upon receiving an open command from a user instructing to open a first document file for a first electronic document stored in an auxiliary storage device mounted on the computing device, reads the first document file and performs rendering to display the first electronic document, thereby displaying the first electronic document on a screen; a verification unit that, when the first electronic document is displayed on the screen, checks whether an image set exists in which two or more images overlap each other on the first electronic document; a generation unit that, if the verification result of the verification unit confirms that the first image set exists, performs image correction in a manner that removes the area overlapping with the top image for the remaining images excluding the topmost image among the two or more images constituting the first image set, and then generates a bitmap for the corrected remaining images; and for the remaining images loaded for image rendering on RAM (Random Access Memory) mounted on the computing device. It includes a replacement unit that replaces the bitmap with the bitmap for the corrected residual images.

[0010] In addition, a method of operation of a computing device capable of saving memory by correcting a bitmap for images overlapping each other on an electronic document according to an embodiment of the present invention comprises: a step of, when an open command is received from a user instructing to open a first document file for a first electronic document stored in an auxiliary storage device mounted on the computing device, reading the first document file and performing rendering to display the first electronic document, thereby displaying the first electronic document on a screen; a step of, when the first electronic document is displayed on the screen, checking whether there exists an image set in which two or more images overlap each other on the first electronic document; a step of, if it is confirmed as a result of the checking step that the first image set exists, performing image correction on the remaining images excluding the topmost image among the two or more images constituting the first image set, in a manner that removes the area overlapping with the top image, and then generating a bitmap for the corrected remaining images; and, on the RAM mounted on the computing device, the bitmap for the remaining images loaded for image rendering, to the corrected remaining images Includes a step to replace with a bitmap. Effects of the invention

[0011] The present invention provides a computing device and a method of operation that can save memory by correcting bitmaps of images overlapping each other on an electronic document, thereby supporting the saving of memory capacity used when an electronic document is displayed on the computing device. Brief explanation of the drawing

[0012] FIG. 1 is a diagram illustrating the structure of a computing device that can save memory by correcting bitmaps of images that overlap each other on an electronic document, according to an embodiment of the present invention. FIGS. 2 and FIGS. 3 are drawings for explaining the operation of a computing device that can save memory by correcting bitmaps of images that overlap each other on an electronic document, according to an embodiment of the present invention. FIG. 4 is a flowchart illustrating a method of operation of a computing device that can save memory by correcting bitmaps of images overlapping each other on an electronic document, according to an embodiment of the present invention. Specific details for implementing the invention

[0013] Embodiments according to the present invention will be described in detail below with reference to the accompanying drawings. This description is not intended to limit the present invention to specific embodiments and should be understood to include all modifications, equivalents, and substitutions that fall within the spirit and scope of the present invention. Similar reference numerals have been used for similar components in describing each drawing, and unless otherwise defined, all terms used in this specification, including technical or scientific terms, have the same meaning as generally understood by a person skilled in the art to which the present invention pertains.

[0014] In this document, when a part is described as "including" a component, it means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Furthermore, in various embodiments of the present invention, each component, functional block, or means may be composed of one or more sub-components, and the electrical, electronic, or mechanical functions performed by each component may be implemented by various known devices or mechanical elements, such as electronic circuits, integrated circuits, and ASICs (Application Specific Integrated Circuits), and may be implemented separately or two or more may be integrated into one.

[0015] Meanwhile, the blocks in the attached block diagram or the steps in the flowchart may be interpreted as computer program instructions that perform designated functions by being loaded into the processor or memory of data-processing equipment, such as general-purpose computers, specialized computers, portable notebook computers, and network computers. Since these computer program instructions may be stored in memory provided in a computer device or in memory readable by a computer, the functions described in the blocks in the block diagram or the steps in the flowchart may be produced as manufactured products containing means of instruction to perform them. Furthermore, each block or each step may represent a module, segment, or part of code containing one or more executable instructions for executing a specific logical function(s). Also, it should be noted that in some alternative embodiments, the functions mentioned in the blocks or steps may be executed in a different order than the prescribed order. For example, two blocks or steps shown in succession may be performed substantially simultaneously or in reverse order, and in some cases, some blocks or steps may be omitted.

[0016] FIG. 1 is a diagram illustrating the structure of a computing device that can save memory by correcting bitmaps of images that overlap each other on an electronic document, according to an embodiment of the present invention.

[0017] Referring to FIG. 1, a computing device (110) according to the present invention includes a display unit (111), a verification unit (112), a generation unit (113), and a replacement unit (114).

[0018] When the display unit (111) receives an open command from a user instructing to open a first document file for a first electronic document stored in an auxiliary storage device mounted on a computing device (110), it reads the first document file and performs rendering to display the first electronic document, thereby displaying the first electronic document on the screen.

[0019] Here, the auxiliary storage device refers to a non-volatile storage medium for storing data of a computing device (110), and may be an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0020] Specifically, in order to perform rendering of the first electronic document, the display unit (111) reads the first document file, loads the data of the first electronic document onto the RAM (Random Access Memory), which is a main memory device mounted on the computing device (110), and then uses a method of accessing the data of the first electronic document through I / O (Input / Output) with the RAM. At this time, if certain images are inserted in the first electronic document, each of the images is composed of a bitmap and exists in a loaded state on the RAM.

[0021] Thus, when the first electronic document is displayed on the screen, the verification unit (112) checks whether there is an image set in which two or more images overlap each other on the first electronic document.

[0022] If, as a result of the verification by the verification unit (112), it is confirmed that there is a first image set in which two or more images overlap each other on the first electronic document as in the example shown in FIG. 2, the generation unit (113) performs image correction on the remaining images, excluding the topmost image among the two or more images constituting the first image set, by removing the area that overlaps with the top image, and then generates a bitmap for the corrected remaining images.

[0023] At this time, according to one embodiment of the present invention, the generation unit (113) may include an identification unit (115), a correction unit (116), and a bitmap generation unit (117).

[0024] The identification unit (115), when it is confirmed by the verification unit (112) that the first image set exists, identifies the remaining images among two or more images constituting the first image set, excluding the image located at the top.

[0025] The correction unit (116) performs image correction for each of the remaining images by identifying all upper images having the z-order of the upper layer in the first image set based on the z-order of each remaining image, and then identifying and removing all areas that overlap with the identified upper images.

[0026] The bitmap generation unit (117) generates a bitmap for each of the corrected remaining images when image correction for each of the remaining images is completed.

[0027] At this time, according to one embodiment of the present invention, when image correction for each of the remaining images is completed, the bitmap generation unit (117) generates a square-shaped bitmap that surrounds the outer edge of each of the corrected remaining images, and if there is a blank area on the bitmap of any one of the corrected remaining images, the bitmap can be reconstructed into two or more divided bitmaps by dividing the bitmap into two or more square-shaped parts that minimally include the blank area.

[0028] The replacement unit (114) replaces the bitmap for the remaining images loaded for image rendering on the RAM mounted on the computing device with the bitmap for the corrected remaining images.

[0029] Hereinafter, with reference to FIG. 2, the operation of the computing device (110) according to the present invention will be described in detail by way of example.

[0030] First, let us assume that the first image set (211, 212, 213) is included in the first electronic document as shown in the example in FIG. 2, where images 1 (211), 2 (212), and 3 (213) overlap each other, and that the first image set (211, 212, 213) is confirmed to exist in the first electronic document through the verification unit (112).

[0031] Then, the identification unit (115) can identify the remaining images (212, 213) excluding the topmost image (211) among the images (211, 212, 213) constituting the first image set (211, 212, 213).

[0032] After that, the correction unit (116) can perform image correction for each of the remaining images (212, 213) by identifying all upper images having the z-order of the upper layer in the first image set (211, 212, 213) based on the z-order of each remaining image, and then identifying and removing all areas that overlap with the identified upper images.

[0033] Here, z-order refers to the sequence number in the z-axis direction of objects such as images inserted in an electronic document, that is, the overlap sequence number.

[0034] In this regard, the correction unit (116) can perform image correction for image 2 (212) by identifying the upper image having the z-order of the upper layer in the first image set (211, 212, 213) as image 1 (211) based on the z-order of image 2 (212), and then identifying the area in image 2 (212) that overlaps with image 1 (211) and removing all of it.

[0035] Additionally, the correction unit (116) can perform image correction for image 3 (213) by identifying the upper image having the z-order of the upper layer in the first image set (211, 212, 213) based on the z-order of image 3 (213) as image 1 (211) and image 2 (212), and then identifying the area overlapping with image 1 (211) and image 2 (212) in image 3 (213) and removing all of them. Specifically, the process of the correction unit (116) performing image correction on image 3 (213) is explained with reference to FIG. 3. The correction unit (116) can perform image correction on image 3 (213) by identifying the upper image having the z-order of the upper layer in the first image set (211, 212, 213) as image 1 (211) and image 2 (212) based on the z-order of image 3 (213), and then identifying the area (311) that overlaps with image 1 (211) and image 2 (212) in image 3 (213) as shown in the figure of reference numeral 310, and removing all of them.

[0036] In this way, when image correction for each of image 2 (212) and image 3 (213) is completed through the correction unit (116), the bitmap generation unit (117) can generate bitmaps for each of the corrected image 2 (212) and image 3 (213).

[0037] At this time, since the bitmap is image data composed of a rectangular shape, the bitmap generation unit (117) can generate a rectangular bitmap that surrounds the outer edges of each of the corrected images 2 (212) and 3 (213) when the image correction for each of the images 2 (212) and 3 (213) is completed through the correction unit (116).

[0038] At this time, according to one embodiment of the present invention, the bitmap generation unit (117) generates a square-shaped bitmap that surrounds the outer edges of each of the corrected image 2 (212) and image 3 (213), and if there is a blank area on the bitmap of a specific image, the bitmap can be reconstructed into two or more divided bitmaps by dividing the bitmap into two or more square-shaped parts that minimally include the blank area.

[0039] In this regard, let us assume that, as shown in the figure in FIG. 3, an area (311) overlapping with the upper images is identified for image 3 (213), and that this part is completely removed. Then, the bitmap generation unit (117) can generate a square-shaped bitmap that surrounds the outer area of ​​the corrected image 3 (213) for the corrected image 3 (213).

[0040] At this time, the bitmap generated for the corrected image 3 (213) is a rectangular shape that surrounds the outer area of ​​the corrected image 3 (213), so it can be composed of a bitmap that includes the area (311) removed through the correction unit (116) as a margin, as shown in the figure illustrated in reference numeral 310.

[0041] Then, the bitmap generation unit (117) can reconstruct the bitmap of the corrected image 3 (213) into two rectangular bitmaps (321, 322) by dividing it into two or more rectangular parts (321, 322) that include a minimum margin area (311), as shown in the figure illustrated in reference numeral 320.

[0042] In this way, since the corrected image 2 (212) also has a blank area when composed of a square-shaped bitmap, the bitmap generating unit (117) can reconstruct the bitmap of the corrected image 2 (212) into two square-shaped bitmaps by dividing it into two or more square-shaped parts that include the minimum blank area, as shown in the figure of reference numeral 320.

[0043] Thus, when bitmaps for corrected image 2 (212) and image 3 (213) are generated through the identification unit (115), correction unit (116), and bitmap generation unit (117) included in the generation unit (113), the replacement unit (114) can replace the bitmaps for image 2 (212) and image 3 (213) loaded for image rendering on the RAM mounted on the computing device (110) with the bitmaps for corrected image 2 (212) and corrected image 3 (213), respectively.

[0044] Thus, when the bitmaps for Image 2 (212) and Image 3 (213) loaded in RAM are replaced with the bitmaps for Corrected Image 2 (212) and Corrected Image 3 (213), respectively, through the replacement unit (114), the display unit (111) can perform rendering for Image 2 (212) and Image 3 (213) using the bitmaps for Corrected Image 2 (212) and Corrected Image 3 (213) loaded in RAM when a situation arises where the first electronic document needs to be re-rendered as a user applies commands such as performing page scrolling or zooming in and out on the screen for the first electronic document.

[0045] These bitmaps for corrected image 2 (212) and corrected image 3 (213) are bitmaps that are smaller in size than the bitmaps for original image 2 (212) and original image 3 (213), and since the size of the bitmap data temporarily stored in RAM is reduced by that amount, the available capacity of RAM is ultimately increased by the amount that the size of the bitmap data is reduced.

[0046] According to one embodiment of the present invention, the bitmap generation unit (117) may not generate a bitmap for the first remaining image when the entire area of ​​the first remaining image is removed as it is identified through the correction unit (116) that the entire area of ​​the first remaining image, which is one of the remaining images, overlaps with all the upper images. At this time, when the replacement unit (114) replaces the bitmap for the remaining images loaded for image rendering on the RAM mounted on the computing device (110) with the bitmap for the corrected remaining images, the bitmap for the first remaining image may be deleted from the RAM without replacing the bitmap for the first remaining image.

[0047] In this regard, in the figure of FIG. 2, if it is assumed that image 3 (213) is positioned so as to be completely obscured at the bottom of image 1 (211) and image 2 (212), unlike the example of FIG. 2, the correction unit (116) can identify the entire area of ​​image 3 (213) as an area that overlaps with the upper images and remove the entire area of ​​image 3 (213).

[0048] In this way, when the entire area of ​​image 3 (213) is completely removed, the bitmap generation unit (117) may not generate a bitmap for image 3 (213). Then, when the replacement unit (114) replaces the bitmap for image 2 (212) and image 3 (213) loaded for image rendering on the RAM mounted on the computing device (110) with the bitmap for the corrected image, the bitmap for image 3 (213) may be deleted from the RAM without replacing the bitmap for image 3 (213).

[0049] According to one embodiment of the present invention, the computing device (110) may further include a restoration unit (118).

[0050] The restoration unit (118) can read the first document file and replace the bitmap for the corrected remaining images loaded on the RAM mounted on the computing device (110) with the bitmap for the remaining images again when an editing action occurs on any one of the images constituting the first image set on the first electronic document by the user after the bitmap for the remaining images loaded on the RAM mounted on the computing device (110) has been replaced with the bitmap for the corrected remaining images through the replacement unit (114).

[0051] In this regard, let us assume a situation in which, as in the example above, the bitmap for image 2 (212) and image 3 (213) loaded for image rendering on the RAM mounted on the computing device (110) through the replacement part (114) is replaced with the bitmap for corrected image 2 (212) and corrected image 3 (213). At this time, when an editing action (e.g., moving the image to another location, changing the size of the image, or deleting the image) occurs on any one of the images constituting the first image set (211, 212, 213) on the first electronic document by the user, the bitmap of the corrected image 2 and 3 (212, 213) loaded on RAM is not a bitmap of the complete image, so it is difficult to perform editing processing according to the user's editing action. Therefore, the restoration unit (118) can read the first document file stored in the auxiliary storage device again and replace the bitmap of the corrected image 2 (212) and corrected image 3 (213) loaded on RAM mounted on the computing device (110) with the bitmap of the original image 2 (212) and original image 3 (213) before correction.

[0052] FIG. 4 is a flowchart illustrating a method of operation of a computing device that can save memory by correcting bitmaps of images overlapping each other on an electronic document, according to an embodiment of the present invention.

[0053] In step (S410), when an open command is received from a user instructing to open a first document file for a first electronic document stored in an auxiliary storage device mounted on the computing device, the first document file is read and rendering is performed to display the first electronic document, thereby displaying the first electronic document on the screen.

[0054] In step (S420), when the first electronic document is displayed on the screen, it is checked whether there is an image set in which two or more images overlap each other on the first electronic document.

[0055] In step (S430), if it is confirmed that a first image set exists as a result of the verification in step (S420), image correction is performed on the remaining images excluding the topmost image among the two or more images constituting the first image set, in a manner that removes the area overlapping with the top image, and then a bitmap for the corrected remaining images is generated.

[0056] In step (S440), the bitmap for the remaining images loaded for image rendering on the RAM mounted on the computing device is replaced with the bitmap for the corrected remaining images.

[0057] At this time, according to one embodiment of the present invention, in step (S430), if it is confirmed that the first image set exists as a result of the confirmation in step (S420), the method may include: a step of identifying the remaining images excluding the topmost image among two or more images constituting the first image set; a step of performing image correction for each of the remaining images by confirming all top images having the z-order of the upper layer in the first image set based on the z-order of each remaining image, and then identifying and removing all areas that overlap with the confirmed top images; and a step of performing bitmap generation for each of the corrected remaining images when the image correction for each of the remaining images is completed.

[0058] At this time, according to one embodiment of the present invention, the step of performing bitmap generation is to generate a rectangular bitmap surrounding the outer edge of each of the corrected remaining images when image correction for each of the remaining images is completed, and if a blank area exists on the bitmap of any one of the corrected remaining images, the bitmap can be reconstructed into two or more divided bitmaps by dividing the bitmap into two or more rectangular parts that minimally include the blank area.

[0059] In addition, according to one embodiment of the present invention, the step of performing bitmap generation may not generate a bitmap for the first remaining image if the entire area of ​​the first remaining image is removed as it is identified through the step of performing image correction that the entire area of ​​the first remaining image, which is one of the remaining images, exists overlapping with all the upper images.

[0060] At this time, in step (S440), when replacing the bitmap for the remaining images loaded for image rendering on the RAM mounted on the computing device with the bitmap for the corrected remaining images, the bitmap for the first remaining image can be deleted from the RAM without replacing the bitmap for the first remaining image.

[0061] Additionally, according to one embodiment of the present invention, the method of operating the computing device may further include the step of reading the first document file and replacing the bitmap for the corrected remaining images loaded on the RAM mounted on the computing device with the bitmap for the remaining images again when an editing action occurs on any one of the images constituting the first image set on the first electronic document by the user after the bitmap for the remaining images loaded on the RAM mounted on the computing device for image rendering is replaced with the bitmap for the remaining images through step (S440).

[0062] Hereinafter, a method of operation of a computing device according to an embodiment of the present invention has been described with reference to FIG. 4. Here, since the method of operation of a computing device according to an embodiment of the present invention may correspond to the configuration of the operation of the computing device (110) described using FIGs. 1 to 3, a more detailed description thereof will be omitted.

[0063] A method of operation of a computing device according to one embodiment of the present invention can be implemented as a computer program stored in a storage medium for execution through combination with a computer.

[0064] In addition, a method of operation of a computing device according to an embodiment of the present invention may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc., either individually or in combination. The program instructions recorded on the medium may be those specifically designed and configured for the present invention, or they may be those known and available to those skilled in the art of computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs and DVDs; magneto-optical media such as floptical disks; and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, and flash memory. Examples of program instructions include machine code, such as that generated by a compiler, as well as high-level language code that can be executed by a computer using an interpreter, etc.

[0065] As described above, the present invention has been explained by specific details such as specific components, limited embodiments, and drawings; however, this is provided merely to aid in a more comprehensive understanding of the invention, and the invention is not limited to the above embodiments. A person skilled in the art can make various modifications and variations from this description.

[0066] Accordingly, the scope of the present invention is not limited to the described embodiments, and all things equivalent to or having equivalent variations to the claims set forth below, as well as the claims set forth below, shall be considered to fall within the scope of the concept of the present invention. Explanation of the symbols

[0067] 110: Computing device 111: Display unit 112: Confirmation unit 113: Generation part 114: Replacement part 115: Identification unit 116: Correction unit 117: Bitmap Generation Unit 118: Restoration Unit

Claims

Claim 1 A computing device capable of saving memory by correcting bitmaps for images that overlap each other on an electronic document, comprising: a display unit that, upon receiving an open command from a user instructing to open a first document file for a first electronic document stored in an auxiliary storage device mounted on the computing device, reads the first document file and performs rendering to display the first electronic document, thereby displaying the first electronic document on a screen; a verification unit that, when the first electronic document is displayed on the screen, checks whether an image set exists in which two or more images overlap each other on the first electronic document; a generation unit that, if the verification result of the verification unit confirms that a first image set exists, performs image correction on the remaining images excluding the topmost image among the two or more images constituting the first image set, by removing the area overlapping with the top image, and then generates a bitmap for the corrected remaining images; and, on the RAM (Random Access Memory) mounted on the computing device, the bitmap for the remaining images loaded for image rendering, the corrected remaining A computing device comprising: a replacement unit that replaces images with bitmaps; and a restoration unit that, through the replacement unit, when an editing action occurs by the user on any one of the images constituting the first image set in the first electronic document after the bitmap for the remaining images loaded for image rendering on the RAM mounted on the computing device is replaced with the bitmap for the corrected remaining images, reads the first document file and replaces the bitmap for the corrected remaining images loaded on the RAM mounted on the computing device with the bitmap for the remaining images again. Claim 2 A computing device according to claim 1, wherein the generating unit, when confirmed by the confirmation result of the confirmation unit that the first image set exists, identifies the remaining images excluding the topmost image among two or more images constituting the first image set; a correction unit that performs image correction for each of the remaining images by confirming all top images having the z-order of the upper layer in the first image set based on the z-order of each remaining image, and then identifying and removing all areas that overlap with the confirmed top images; and a bitmap generating unit that generates a bitmap for each of the corrected remaining images when image correction for each of the remaining images is completed. Claim 3 A computing device according to paragraph 2, wherein the bitmap generating unit, when image correction for each of the remaining images is completed, generates a rectangular bitmap surrounding the outer edge of each of the corrected remaining images, and if a blank area exists on the bitmap of any one of the corrected remaining images, the bitmap is reconstructed into two or more divided bitmaps by dividing the bitmap into two or more rectangular parts that minimally include the blank area. Claim 4 In paragraph 2, the bitmap generating unit does not generate a bitmap for the first remaining image when the entire area of ​​the first remaining image is removed as it is identified through the correction unit that the entire area of ​​the first remaining image, which is one of the remaining images, exists overlapping with all the upper images, and at this time, when the replacement unit replaces the bitmap for the remaining images loaded for image rendering on the RAM mounted on the computing device with the bitmap for the corrected remaining images, the bitmap for the first remaining image is deleted from the RAM without replacing the bitmap for the first remaining image. Claim 5 delete Claim 6 A method of operation of a computing device capable of saving memory by correcting bitmaps for images that overlap each other on an electronic document, comprising: a step of, upon receiving an open command from a user instructing to open a first document file for a first electronic document stored in an auxiliary storage device mounted on the computing device, reading the first document file and performing rendering to display the first electronic document, thereby displaying the first electronic document on a screen; a step of, upon the first electronic document being displayed on the screen, checking whether there exists an image set in which two or more images overlap each other on the first electronic document; a step of, if it is confirmed as a result of the checking step that the first image set exists, performing image correction on the remaining images excluding the topmost image among the two or more images constituting the first image set, in a manner that removes the area overlapping with the top image, and then generating a bitmap for the corrected remaining images; wherein the bitmap for the remaining images loaded for image rendering on the RAM (Random Access Memory) mounted on the computing device is the corrected remaining A method of operation of a computing device comprising: a step of replacing the bitmap for the images with a bitmap for the images; and, after the bitmap for the remaining images loaded for image rendering on RAM mounted on the computing device through the replacement step is replaced with the bitmap for the corrected remaining images, when an editing action occurs by the user on any one of the images constituting the first image set on the first electronic document, the step of reading the first document file and replacing the bitmap for the corrected remaining images loaded on RAM mounted on the computing device with the bitmap for the remaining images again. Claim 7 In claim 6, the generating step comprises: a step of identifying the remaining images excluding the topmost image among two or more images constituting the first image set when it is confirmed that the first image set exists as a result of the verification step; a step of performing image correction for each of the remaining images by identifying all top images having the z-order of the upper layer in the first image set based on the z-order of each remaining image, and then identifying and removing all areas that overlap with the identified top images; and a step of performing bitmap generation for each of the corrected remaining images when image correction for each of the remaining images is completed. Claim 8 A method of operation of a computing device according to claim 7, wherein the step of performing bitmap generation is characterized by generating a rectangular bitmap surrounding the outer edge of each of the corrected residual images when image correction for each of the residual images is completed, and, if a blank area exists on the bitmap of any one of the corrected residual images, reconstructing the bitmap into two or more divided bitmaps by dividing the bitmap into two or more rectangular parts that minimally include the blank area. Claim 9 In claim 7, the step of performing bitmap generation is characterized by not generating a bitmap for the first remaining image when the entire area of ​​the first remaining image is removed as it is identified through the step of performing image correction that the entire area of ​​the first remaining image, which is one of the remaining images, exists overlapping with all the upper images, and the replacement step is characterized by deleting the bitmap for the first remaining image from the RAM without replacing the bitmap for the first remaining image when replacing the bitmap for the remaining images loaded for image rendering on the RAM mounted on the computing device with the bitmap for the corrected remaining images. Claim 10 delete Claim 11 A computer-readable recording medium having a computer program for executing the method of any one of paragraphs 6 through 9 in combination with a computer. Claim 12 A computer program stored on a storage medium for executing the method of any one of paragraphs 6 through 9 through combination with a computer.

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