Automatic focusing method of rock debris image online acquisition device

Abstract

The invention discloses an automatic focusing method of a rock debris image on-line acquisition device, which comprises the following steps of: assigning an initial initial focal length value, starting the on-line acquisition device, and driving the on-line acquisition device to return to an initial initial focal length point position by a focusing mechanism; the focusing mechanism is driven at the minimum focusing step length, collects a first image and a second image and calculates the definition; if the definition of the second image is smaller than that of the first image, modifying the initial focal length value; if the definition of the second image is greater than the definition of the first image, traversing focal length point locations to sequentially collect images of the focal length point locations until the definition of the frame image is smaller than that of the previous frame image, and determining that the image with the optimal definition is the previous frame image; when the definitions of three continuous focal length point positions are equal, determining that the lens is out of focus, and switching to out-of-focus adjustment; acquiring an image at the optimal focal length value; according to the focusing method, fine search is carried out from the near end to the far end according to the fine search step length, the search direction is accurately and rapidly determined, the optimal focal length value is locked, and the focusing efficiency is high.

Claims

1. An automatic focusing method for an online collection device for rock cuttings images, wherein the online collection device is driven step by a focusing mechanism, characterized in that: Includes the following steps and contents: (A) assigning an initial starting focal length value, starting the online acquisition device, driving the online acquisition device to return to the initial starting focal length point by the focusing mechanism, turning on the white light, and providing a focusing light source; (B) The online acquisition device captures the first frame image of the starting focal length value, and the focusing mechanism drives the online acquisition device to move to the next focal length point at the far end with the focusing step length of the critical threshold value, and captures the second frame image, and calculates the clarity of the first image and the second image; (C) Searching for the best definition image based on the definition comparison result includes the following contents: (c1) If the clarity of the second image is less than that of the first image, the starting focal length value is modified, and the focusing mechanism drives the online acquisition device to return to the newly set starting focal length point, and the operation returns to step (B); (c2) If the clarity of the second image is greater than that of the first image, the focusing mechanism drives the online acquisition device to move to the far end to traverse the focal points with a focusing step length of a critical threshold, collects images of the focal points in sequence and analyzes their image clarity, and compares the clarity of the current frame image with that of the previous frame image, until the clarity of the current frame image is less than that of the previous frame image, then the best clarity image is the previous frame image; (c3) Record the clarity of each focal point. When the clarity of three consecutive focal points is equal, it is determined that the lens is out of focus, and the fine search is stopped and the focus adjustment is switched to focus adjustment. (D) Based on the best definition image searched in steps (B) and (C), the online acquisition device returns to the focal point of the best definition image and takes a photo to collect the corresponding sample image.

2. The automatic focusing method of the online rock cuttings image acquisition device according to claim 1, characterized in that: In the step (c1), the starting focal length value is automatically modified by decreasing, and a new starting focal length value is assigned by reducing the focusing step length of the original starting focal length value by a critical threshold.

3. The automatic focusing method of the online rock cuttings image acquisition device according to claim 1, characterized in that: The defocus adjustment includes the following contents and steps: S1, assigning a starting focal length value with the minimum focal length value of the online acquisition device, and traversing the focal length points toward the far end with the maximum focusing step length; S2. If the image clarity of the current focal point is less than that of the previous focal point, the focusing mechanism drives the online acquisition device to return to the second focal point in front, updates the focusing step size in a decreasing manner, and traverses the focal points to the far end with the new focusing step size; Before updating the focusing step, step gradient identification is performed. When the focusing step is the minimum focusing step, the image clarity of the current focal point is less than the image clarity of the previous focal point, and the focal length value of the best clarity image is the focal length value of the previous focal point. The online acquisition device stops at the focal length value of the best clarity image to perform sample image acquisition.

4. The automatic focusing method of the online rock cuttings image acquisition device according to claim 3, characterized in that: The focus step size in step S2 is updated in a half-decreasing method.

5. The automatic focusing method of the online rock cuttings image acquisition device according to claim 1, characterized in that: During the focusing process, all the collected images are denoised by the jitter algorithm before the clarity is calculated.

Images