KR-20260063393-A - Apparatus and method for detecting defect pixels and apparatus and method for correcting defect pixels

Abstract

A defective pixel detection device comprises an image sensor that captures a test image and generates an image frame; a DP detection unit that detects defective pixels from pixels included in the image frame; a DP map generation unit that generates a DP map by accumulating the count of the detected defective pixels for each pixel location across a plurality of image frames and stores the generated DP map in storage; a DP alignment unit that sorts the defective pixels in order from highest to lowest accumulated counts; and a DP location storage unit that stores the locations of the sorted defective pixels in storage.

Inventors

• 이창민
• 정갑천

Assignees

• 한화비전 주식회사

Dates

Publication Date

20260507

Application Date

20241030

Claims (6)

1. A defective pixel detection device comprising a processor and a memory for storing instructions executable by said processor, An image sensor that captures a test image and generates an image frame; A DP detection unit that detects defective pixels from pixels included in the image frame above; A DP map generation unit that generates a DP map by accumulating the count of the detected defective pixels for each pixel location for a plurality of image frames, and stores the generated DP map in storage; A DP alignment unit that aligns the defective pixels from highest to lowest order based on the accumulated counts; and A defective pixel detection device comprising a DP location storage unit that stores the locations of the aligned defective pixels in the storage.
2. In claim 1, the DP location storage unit is, A defective pixel detection device that stores defective pixels up to a predetermined correction limit, starting from the order of the highest accumulated count among the above-mentioned aligned defective pixels, in the storage.
3. In claim 1, the DP map generating unit A memory read control unit that reads the current count of the current pixel recorded in the storage above; An index update unit that increases the read current count when the current pixel is determined to be a defective pixel by the DP detection unit; and A defective pixel detection device comprising a memory recording control unit that records the increased count for the current pixel in the storage.
4. A defective pixel correction device comprising a processor and a memory for storing instructions executable by said processor, An image sensor that captures real-time images and generates image frames; A DP information reading unit that reads DP information stored in storage; System monitor that monitors system resources; A correction limit determining unit that variably determines a correction limit according to the above system resources; and A defective pixel correction device comprising a DP correction unit that, within the range of the above-determined correction limit, compares the position of a current pixel included in the image frame with the position of a defective pixel included in the DP information, and corrects the current pixel when the two positions match each other.
5. In paragraph 4, A defective pixel correction device further comprising a real-time correction unit that performs real-time dynamic correction on an image frame in which defective pixels have been corrected in the above-mentioned DP correction unit.
6. In paragraph 5, A defective pixel correction device in which, as the correction limit increases, the correction strength used for the real-time dynamic correction decreases, and as the correction limit decreases, the correction strength increases.

Description

Apparatus and method for detecting defect pixels and apparatus and method for correcting defect pixels The present invention relates to an apparatus and method for detecting defective pixels occurring in an image sensor and correcting the detected defective pixels. Defective pixels inevitably occur during the manufacturing of image sensors, and consequently, defects in pixel values are bound to occur at fixed locations in the captured image. Therefore, in order to obtain a visually flawless image by concealing these defective pixels despite their presence, it is necessary to perform the processes of detecting these defective pixels and correcting the detected defective pixels together. Generally, methods for correcting defective pixels are broadly divided into static correction and dynamic correction methods. The static correction method described above is performed at the factory before product shipment using black image frames and white image frames. As a result, the coordinates of black and white defective pixels are stored in a storage device, and correction is performed on the pixels located at the stored coordinates. In contrast, the dynamic correction method detects defective pixels in real-time for each individual frame of a captured image. Because this method detects defective pixels in real-time and corrects their values using surrounding pixels, it is useful in that it does not require separate pre-shipment work at the factory like the static correction method and there is no limit to the number of defective pixels that can be corrected. However, detecting defective pixels in image frames in real-time is not easy, and false positives (misidentifications) can cause degradation in the original image quality. However, as a prerequisite for such defective pixel correction, the difficulty in detecting defective pixels lies in finding the optimal conditions under which defects occur. This is because the number of static defective pixels is limited due to hardware constraints, making it difficult to find optimal conditions within that limited range. Consequently, the complex process of searching for defective pixels by assigning an appropriate sensor gain and adjusting exposure settings accordingly can lead to inaccurate detection, particularly when there is a wide variety of sensor types, which can degrade the effectiveness of defective pixel correction. FIG. 1 is a block diagram illustrating the configuration of a defective pixel detection device according to one embodiment of the present invention. FIG. 2 is a block diagram illustrating the configuration of a DP detection unit included in the defective pixel detection device of FIG. 1. FIG. 3 is a block diagram illustrating the configuration of a DP map generation unit included in the defective pixel detection device of FIG. 1. FIG. 4 is a diagram showing the structure of a DP map according to one embodiment of the present invention. Figure 5 is a diagram illustrating a data storage format according to the structure of the DP map of Figure 4. FIG. 6a is a diagram illustrating the distribution of pixel values within an image frame at time t, and FIG. 6b is a diagram illustrating the distribution of pixel values within an image frame at time t+1 after the above time. FIG. 7 is a diagram showing the scanning order of pixels included in an image frame according to one embodiment of the present invention. FIG. 8 is a block diagram illustrating the configuration of a defective pixel correction device that actually corrects defective pixels using DP information provided from the defective pixel detection device of FIG. 1. Figure 9 is a graph showing allowable correction limits that vary depending on current system resources. FIG. 10 is a drawing illustrating an example of an implementation of a computing device that realizes the defective pixel detection device of FIG. 1 or the defective pixel correction device of FIG. 8. FIG. 11a is a flowchart illustrating a defective pixel detection method according to one embodiment of the present invention, and FIG. 11b is a flowchart illustrating a defective pixel correction method according to one embodiment of the present invention. The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components. Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a