Introduction to ColorChecker Test Card

ColorChecker test card, containing six levels of grayscale color blocks, additive primary colors (red, green, blue), subtractive primary colors (yellow, magenta, cyan), as well as skin tone and simulated natural object real colors. The label has 24 solid color blocks, labeled 1-24 from left to right and top to bottom. So it's also called a 24 color card. For the testing of camera color and white balance, we used ColorChecker test cards to compare the corresponding white balance modes in different environments. On the one hand, we can observe the model's ability to reproduce various colors, and on the other hand, we can observe their white balance accuracy.

Application areas of ColorChecker test card

Digital camera: Check the color reproduction of the camera, lens, and optical system, calibrate the image color of the digital camera, compare and test the white balance of the target, and reproduce real colors in the color reproduction system.

Image and video: Check the quality of static and dynamic color reproduction of the camera, inspect the color reproduction of the camera and its optical system, and the color reproduction of the projection system.

Electronics industry: color reproduction for detecting scanners, monitors, and monitors.

Printing industry: Testing any printing and proofing program, inspecting film, light, color filters, and paper.

Usage of ColorChecker Test Card

(1) Color reproduction

The Colorchecker test card can accurately reproduce colors under any lighting conditions. The first thing you want to shoot should be the ColorChecker standard color card. The specific steps are as follows:

1. Place the ColorChecker test card at the camera location (without filling the viewfinder)

2. Ensure that the camera can capture all color blocks

3. Place the ColorChecker test card in a representative part of the composition, avoiding shadows or overexposed highlights

4. Do not let the light reflected by other objects project onto the color chart

5. Take photos with color swatches

6. When opened in Photoshop, there will be a built-in reference point

7. Use a color picker to sample the black block. The difference between RGB should be within 7 units, approximately 245

8. Take a sample of the white block. The value of RGB is approximately 245

9. Check for color cast. Select the gray color block in the middle, with an RGB value of approximately 128, and the difference between them should not exceed 7

10. If the reading deviates significantly, apply a horizontal or curved adjustment back to the above state

11. Save settings. This setting can be used for other shapes under the same lighting conditions.

12. Further visual color matching can be performed using other color blocks.

Attention: A calibrated monitor should be used, and the physical ColorChecker test card should be placed under a standard light source with controllable lighting conditions

(2) By using professional software such as PM5, it is possible to generate customized ICC files for digital cameras

1. When shooting color cards in natural and controllable lighting conditions, pay attention to adjusting the appropriate angle. Do not let the light directly reflect through the color card into the lens, nor do you let the colors reflected by other objects project onto the color card. This may cause significant deviation and lead to significant errors in calculating ICC for PM5;

2. Try to use manual and accurate white balance to lock the white balance as much as possible, such as gray balance card, white balance card, etc.

3. To control the exposure, you can open the histogram for observation and adjust the exposure compensation. It is important to ensure that the color value of the white block reaches between 210-245 for ideal results. However, the requirement for black blocks can be ignored, because for models with higher tolerance, when the white block reaches a measurement of 210-245, the black block is unlikely to be less than 23, but it is easier to achieve for machines with lower tolerance. And the meaning here is actually to control the exposure as much as possible, so that the color blocks in the color chart reach the ideal white and black spots.

4. When shooting, set all contrast and color settings inside the camera to default values, and be careful not to set sharpening options, as this can also affect the color of the captured color chart.

5. It is recommended to ensure that the light on the surface of the color card is evenly distributed and avoid half bright and half dark situations. It is best to use dual light sources, which illuminate the color card from the left and right at a 45 ° angle.