Pixel window

Use Image>Luminance>Pixel window to view the luminance, red channel, green channel or blue channel values for individual pixels. The default value displayed is the luminance value. Pixel Window also calculates the average luminance for a circular area of your choice. Values are displayed in a table.

Useful when you have issues with image segmentation (Kodalith): The Pixel window can help determine how the luminance values vary across the image and provide insights into adjusting the illumination source for better, more uniform illumination.

Luminance

For the pixel located directly under the crosshair cursor:

  • The luminance value is displayed at the center of the Pixel window, highlighted in white.
  • The XY coordinates are displayed to the right of the Pixel Luminance label in the Pixel window.

For a gray scale image, the luminance value is the same as the gray scale value (from 0 to 255).

  • A black pixel has a luminance of 0.
  • A white pixel has a luminance of 255.

The size of the crosshair has no effect on the sampling of the image. As the cursor is moved to the edge of the image the values off the edge of the image are seen in the pixel window as dashes instead of numbers.

  1. Move the cursor over the Pixel window.
  2. Right-click and select Circular Crosshair Average.
  3. Use the mouse wheel or +/- keys to modify the size of the circular cursor. The program highlights all the values of pixels within the circular cursor area.

    The title bar of the Pixel window indicates the average luminance, the number of pixels averaged, the XY coordinates of the pixel located at the center of the circular area.

Red, Green, Blue channel values

You can view the red, green, or blue channel values for individual pixels in a true color or paletted image. The red, green, or blue pixel values are raw values—they are not multiplied by the values used in computing the luminance.

  1. Move the cursor over the Pixel window.
  2. Right-click and select Red Channel/Green Channel/Blue Channel.