JPH04270592A - Evaluation method for solid-state image pickup element - Google Patents

Abstract

PURPOSE:To discriminate a small defect of contrast such as color stain or uneven color being a problem in a color picture resulting from a solid-state image pickup element automatically, quickly and accurately. CONSTITUTION:A color use solid-state image pickup element 1 is divided into plural areas by a picture division means 4, a mean value of color data in each area is calculated by a mean value calculation means 5, the maximum value and the. minimum value of the above mean values between areas are calculated by a comparator means 6, a difference data between the maximum value and the minimum value is calculated by a difference data calculation means 7, the result is compared with a preset threshold level at a comparison discrimination means 8, an electric characteristic of the solid-state image pickup element is discriminated by a discrimination means 9 to discriminate the propriety of the solid-state image pickup element.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state imaging device evaluation method for testing and determining the electrical characteristics of a solid-state imaging device.

0002

2. Description of the Related Art In recent years, solid-state imaging devices have made remarkable advances in the consumer and industrial fields, and in particular, solid-state imaging devices are used almost 100% of the time in consumer video cameras.

[0003] Solid-state image sensors for video cameras are usually colored using color filters and have a structure that allows color signals to be obtained, so regulations regarding the image quality of color images are set in the electrical characteristics. Therefore, it is necessary to accurately and quickly inspect and select products that meet these regulations.

[0004] As means for inspecting and sorting the electrical characteristics of solid-state image sensing devices, it is common to first automatically sort them in a wafer state using a tester, and then after assembly to sort them using a tester or a mounting evaluation device.

[0005] Here, a method for inspecting defects in a solid-state image sensor using a tester will be explained based on the block diagram of FIG. First, image data, which is a signal from the solid-state image sensor 10, is stored for each pixel in the image storage device 11 inside or outside the tester. Next, in order to detect defects in the stored image data, the average value calculation means 12 calculates the average value of the stored image data. Then, the threshold value calculation means 13 calculates a threshold value for defect determination using the average value and a predetermined constant. Further, the comparison means 14 compares the image data stored for each pixel with the threshold value for defect determination for each pixel, and the determination means 15 determines that pixel data exceeding the threshold value is defective.

[0006]

[Problems to be Solved by the Invention] However, according to the conventional evaluation method described above, defects are determined based on a threshold value calculated based on the average value of image data. Although it is possible to determine defects with high contrast, it is impossible to determine defects with low contrast, so-called color spots and color unevenness, which are problematic in color images. Therefore, when inspecting color stains and color unevenness, the solid-state image sensor 1
Image data from 0 must be input into a monitor television and visually checked, making it difficult to perform accurate and rapid sorting.

The present invention solves the above-mentioned problem, and aims to provide a method for evaluating a solid-state image sensor that can automatically determine defects with low contrast, so-called color spots, and color unevenness. be.

[0008]

[Means for Solving the Problems] In order to solve the above problems, the solid-state image sensor evaluation method of the present invention divides image data from a colored solid-state image sensor into a plurality of regions, and For multiple types of color data in each area, calculate the average value within each area for each color data of the same type, compare the above average value for each color data of the same type in all areas, and compare the maximum and minimum values. The value is calculated for all types of color data, the difference data between the above maximum value and the above minimum value is calculated for all types of color data for each color data of the same type, and this difference data and a preset threshold value are calculated. The electrical characteristics are determined by comparison.

[0009]

[Operation] As in the above configuration, the image data from the colored solid-state image sensor is divided into multiple areas, and for each of the multiple types of color data existing in each divided area, each color data of the same type is divided into two or more areas. Calculate the average value within each area, compare the average value for each color data of the same type in all areas, calculate the maximum value and minimum value for all types of color data, and calculate the average value for each color data of the same type. The difference data between the maximum value and the above minimum value is calculated for all types of color data, and this difference data is compared with a preset threshold value to determine whether it is acceptable or not. Automatically determines defects with low contrast, so-called color stains and color unevenness.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a method for evaluating a solid-state image sensor according to an embodiment of the present invention.

In FIG. 1, the entire colorized image data from a solid-state image sensor 1 is taken into a tester, and this image data is stored in an image storage device 2 inside or outside the tester.
is memorized. This stored image data is sent to the color data conversion means 3, where it is converted into a plurality of types of color data. Thereafter, the entire color data is divided into a plurality of regions by the image dividing means 4, and the average value within the region is calculated by the average value calculating means 5 for each color data of the same type. Then, the comparison means 6 compares the average value for each type of color data in the entire area, and calculates the maximum value and minimum value for all types of color data. Then, the difference data calculation means 7 calculates difference data between the maximum value and the minimum value for each type of color data for all types of color data. Thereafter, the comparison/determination means 8 compares the difference data with a preset threshold value, and based on the comparison result, the determination means 9 makes a determination of the electrical characteristics to determine pass/fail.

As described above, according to this embodiment, the difference between the maximum value and the minimum value of color data within the entire image area is calculated, and the difference is compared with a preset threshold value. Defects with low contrast that cause problems in images, so-called color stains and color unevenness, can be automatically determined.

[0013]

As described above, according to the present invention, a colored solid-state image sensor is divided into a plurality of regions, the average value of color data in each region is calculated, and the above average value between the regions is calculated. In order to calculate the maximum and minimum values of , and use the difference data to determine whether the solid-state image sensor passes or fails, a threshold value is calculated from the data average value as in the past, and this threshold value and the above data are used. Unlike the method used to compare average values, the tester can automatically, accurately and quickly determine defects with low contrast that are a problem in color images, so-called color spots and color unevenness.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating a method for evaluating a solid-state image sensor according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a conventional evaluation method for a solid-state image sensor.

[Explanation of symbols]

1 Colored solid-state image sensor 2 Image storage device 3 Color data conversion means 4 Screen splitting means 5 Average value calculation means 6 Comparison means 7 Difference data calculation means 8 Comparative judgment means 9 Judgment means

Claims (1)

[Claims] Claim 1: Colorized image data from a solid-state image sensor is divided into a plurality of regions, and for each of the plurality of types of color data existing in each divided region, each color data of the same type is divided into each region. Calculate the average value for each type of color data, compare the above average value for each color data of the same type in all areas, calculate the maximum value and minimum value for all types of color data, and calculate the maximum value and the above value for each color data of the same type. A solid-state imaging device evaluation method that calculates minimum value difference data for all types of color data and compares this difference data with a preset threshold value to determine electrical characteristics.