Pseudo-Coloring an Image

Use the Pseudo-Color command to “colorize” an active monochrome (Gray Scale 8, Gray Scale 12, Gray Scale 16,  or Floating Point) image.  You might do this to highlight certain features in a gray scale image.  For example, you might want to display all densities above a certain point in red, or, if your imaging device recorded thermal information, all temperatures below a certain point in blue. 

You might also use it to visually amplify specific intensities that are very difficult to distinguish from their surroundings.  For example, features produced by pixels with values of 122 in a field of pixels with similar values would be impossible to see in a gray tone image, but would jump out if that value were to be rendered in color.

When you pseudo-color a monochrome image, you build a special palette through which your monochrome image is displayed.  Pseudo-coloring an image does not modify the pixel values in your image bitmap in any way (it does not convert your image to True Color or Palette, for example).  It simply associates a pseudo-color palette with the image, that interprets the gray-level values in the image as color. 

Pseudo-colored images are very similar in structure to Palette class images, but they differ in a couple of important ways.  First, the pixel values in a pseudo-colored image actually represent continuous-tone intensity information, whereas a Palette image's pixels carry no intensity significance.  Secondly, a Palette image includes a palette table that is actually part of the image file. 

The pseudo-color palette associated with a pseudo-colored image is not a permanent part of the image.  It is a palette that you assign to the image while you work with it in Image-Pro.  Pseudo-color palettes can be saved to a disk file, and later loaded for subsequent use with any monochrome (Gray Scale 8, Gray Scale 12, Gray Scale 16, or Floating Point) image.

The basic steps involved in pseudo-coloring the active, monochrome image are to:

Select the Pseudo button from the Color group on the Adjust ribbon.

Click the drop-down arrow to see the Pseudo-color dialog.

Check the Pseudocolor On/Off to show (or hide) the pseudo-coloring on the image.

Change the color assignments and refine the intensity division widths.  This is done using the Spectrum and Type drop-down menus or the color bar.

The Spectrum drop-down list lets you choose which colors will be used for coloring the images. Choices include Blue to Red, Red to Blue, Cyan, Magenta, and Yellow. You can also define a custom color spectrum.

Type lets you choose RGB, HSI CW, HSI CWW, or a custom type.

Specify the range of intensities you want to pseudo-color.  The intensity range is specified using the Start and End spin buttons.  You can load saved pseudo-color settings using the Load button.

Specify the number of distinct colors you want to associate with the selected intensity range.  The number of colors is selected using the Divisions spin buttons.

Save the settings for future use (with the current image, or with another).  This step is optional.  You do not need to save the pseudo-color assignments in order for them to be applied to the active image. If, however, you want to save it for continuing use or to exchange with a colleague, you need to save it. When you click the Save button, Image-Pro saves the current pseudo-color palette settings.

 

This is a sample of a partial image with the high saturation areas visible:

The Reset button sets the controls back to their default values.