MacBeth Color Checker Test

Owned by Former user (Deleted)
Jun 19, 2013
3 min read

Macbeth Chart Image Tests include color difference test and noise measurements. Color difference test is performed on a single image(current displayed image). Noise measurements are performed on multiple frames in the frameset.

Images can be loaded by clicking Load Imagebutton. Multiple images can be selected using SHIFT or CTRL keys during selection.

Images can also be captured through DevWare by clicking DevWare Image button. Use the spin-box next to the button to define the number of images to be captured.

If multiple frames are loaded, only the current displayed image is processed for Color difference test. All images loaded are used for noise calculations. The loaded chart image is displayed on the left (Chart Image group), and results are displayed on the right (Color Difference Delta-E group). Measurement results are presented in the bottom text browser.

Basic Color Difference and Noise Measurement Steps

Basic measurements can be performed following these steps:

  1. Load the image to be measured using one of the two ways below.

    • Capture from DevWare by clicking the DevWare Image button, DevWare is loaded and the following Setup Sensor dialog will show. Use the spin-box next to the button to define the number of images to be captured. DevWare settings might need adjustments to get proper streaming data. Compose the scene with a Macbeth Chart at the front of camera. Once the scene is composed in DevWare, press the OK button in the Setup Sensor dialog. The dialog will disappear and the DevWare image will be captured and loaded in IQWare. (Please note that once DevWare is running, the Setup Sensor dialog will not be prompted again. Image capturing is done by clicking the DevWare Image button again.)

    • Load existing image file by clicking the Load Image button. A file dialog will be promopted to browse and select the image file for measurement. Multiple images can be selected using SHIFT or CTRL keys during selection.

  2. Regions are denoted by their indexes for the ease of region selection. Regions can be created by the following ways:
    1. Auto detection of MacBeth Color Checker Chart can be started by pressing . It may take up to a minute. User can click the Cancel Auto Detection button to stop the auto detection. Upon, cancellation, the region selection will use the corner assisted transform.
    2. Using the corner assisted transform by pressing . Click and drag the four ellipses on the corners to adjust the detection position of Color Checker.
    3. If the above methods do not provide necessary regions, users can use for individual editing of the regions. Regions can be resized or moved in this mode.

    Detailed illustrated tutorial regarding region selection can be viewed here. (Please use HTML5 compliant browsers).

  3. By using , the regions selection can be reset to the base transform. Previous transforms or selections will be lost.
  4. Click the Process Macbeth Chart button to start the measurements
  5. Use Color and White Balance tab to view color difference results. Corresponding color difference parameter of each color patch will be displayed on the bottom of its corresponding Color Checker box on the right. The smaller the number, the less the color difference is. The left half of each box represents the color captured in the chart image, the right half of each box represents the real color on the MacBeth Color Checker.
  6. Click the Gray Patch tab on the right to switch to plot of gray patches. Gray patches are patch 18-23 of MacBeth Color Checker Chart.
  7. Color difference parameter on display in the chart can be changed using drop-down menu.
  8. Use Signal Noise tab to switch the result views to signal noise measurements. The detailed result table will also change to noise measurement results.
  9. SNR values of R, G, B channels of each color patch will be displayed on its corresponding Color Checker box on the right for RGB image type. For bayer raw images, red, green red, green blue and blue channel values will be reported.
  10. Click the Gray Patch tab on the right to switch to plot of gray patches. Gray patches are patch 18-23 of MacBeth Color Checker Chart.
  11. Click the Save to HTML report (Short key: Ctrl + S) menu under Save button on the top left corner to save the measurements to select destination.
  12. Save to CSV saves only signal noise calculation results.