Method for cutting JPEG picture

A technology in pictures and pictures, applied in the field of image processing, can solve problems such as low efficiency and image quality degradation, and achieve the effects of improving efficiency, reducing CPU consumption, and reducing CPU consumption

Inactive Publication Date: 2010-02-17
GUANGDONG VTRON TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since this method performs a complete JPEG decoding and re-encoding process, it is inefficient and results in a loss of image quality

Method used

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  • Method for cutting JPEG picture
  • Method for cutting JPEG picture

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0056] A cropping method for JPEG images, see Figure 1-A , including the following steps:

[0057] (1) Load the cropped JPEG picture, read the compressed data of the image and the necessary picture information for decoding; the necessary picture information for decoding specifically includes entropy coding table, quantization table, sampling coefficient and width and height information of the picture.

[0058] (2) Carry out entropy decoding to picture compression data, draw the composition data of each MCU; The composition data of described MCU comprises:

[0059] (A) All encoded data before AC component entropy decoding and

[0060] (B) All encoded data before DC component entropy decoding.

[0061] (3) Cropping the picture, determining the MCUs contained in the cropped picture according to the position of the cropped picture in the original picture, and forming an MCU data set with the constituent data of these MCUs.

[0062] Specifically include the following steps:

[...

Embodiment 2

[0072] A cropping method for JPEG images, see Figure 1-B Include the following steps:

[0073] (1) Load the cropped JPEG picture, read the compressed data of the image and the necessary picture information for decoding; the necessary picture information for decoding specifically includes entropy coding table, quantization table, sampling coefficient and width and height information of the picture.

[0074] (2) Carry out entropy decoding to picture compression data, draw the composition data of each MCU; The composition data of described MCU comprises:

[0075] (a) All encoded data before AC component entropy decoding and

[0076] (b) DC component value obtained during entropy decoding.

[0077] (3) cropping picture, according to the position of the picture after cutting in the original picture, determine the MCU that the JPEG picture after cutting comprises, and the composition data of these MCUs forms an MCU data set;

[0078] Specifically include the following steps:

...

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Abstract

The invention discloses a method for cutting a JPEG picture, which comprises the following steps: (1) loading a cut JPEG picture and reading the compressed data of an image and picture information necessary for decoding; (2) carrying out entropy decoding on the compressed data of the picture to obtain the combination data of each MCU; (3) cutting the picture, confirming the MCU contained in the cut picture according to the position of the cut picture in the original picture and leading the combination data of the MCU to form an MCU data set; and (4) writing into a new file according to the MCUdata set of the step (3), the picture information of the step (1) and a file format of the JPEG picture to obtain the cut picture. The invention adopts the MCU as the minimal processing unit to justcarry out entropy decoding on the decoding process of the JPEG picture without carrying out the complete JPEG decoding and recoding process, simply and easily realizes the cutting of the JPEG pictureand improves the efficiency.

Description

technical field [0001] The invention relates to the field of image processing, in particular to a method for cropping JPEG pictures. Background technique [0002] In practical applications, images often need to be cropped, and JPEG is currently one of the most widely used image formats, so cropping JPEG images is a common application. Since the arrangement sequence of each pixel data is disrupted when a JPEG picture is formed, it cannot be cropped directly. The current common method is to first decompress it into RGB dot matrix data arranged in sequence according to the physical position of the image pixels, then cut the dot matrix data, and finally compress the cut small block pictures into JPEG format. Since this method performs a complete JPEG decoding and re-encoding process, it is inefficient and causes image quality degradation. Contents of the invention [0003] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T5/00G06T9/00
Inventor 谷新征董友球荆建营刘先材
Owner GUANGDONG VTRON TECH CO LTD
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