How can I generate Gabor patterns with specified contrasts and save them as pictures?

I need to create pictures with a specific Gabor pattern, with different levels of contrast - from 0% to 100%.

I know there is a "Gabor" function in Matlab, but I did not find a way to define the Gabor's contrast.

I know there is also a PsychToolbox function that creates a Gabor texture on the screen (Screen('DrawTexture', windowPtr, gaborid...), but I do not need to present the Gabors on screen, I need to save bitmap pictures, and I do not know how to capture pictures presented on a running PsychToolbox screen (so a function\code that captures the screen and saves it would be appreciated as well).

Thank you! Genie

[Ralph Andrews]

Hi there,

Any chance you managed this? I need the exact same thing!

Answer 1

[Sreeram]

Hi Genie,

To create Gabor patterns with different contrast levels in MATLAB, you can use the "imadjust" function to modify the contrast of the generated image. Here is how this may be done:

g = gabor(20, 30);
gaborPattern = real(g.SpatialKernel);

% Example for 35% contrast
contrastLevel = 0.35;
adjustedPattern = imadjust(gaborPattern, [0, 1], [0.5 - contrastLevel/2, 0.5 + contrastLevel/2]);
imshow(adjustedPattern)

% Example for 100% contrast
contrastLevel = 1;
adjustedPattern = imadjust(gaborPattern, [0, 1], [0.5 - contrastLevel/2, 0.5 + contrastLevel/2]);
imshow(adjustedPattern)

The "imadjust" function adjusts the contrast by remapping the intensity values of an image. More information on the function is available in the following documentation:

https://www.mathworks.com/help/images/ref/imadjust.html

The image may be saved using the "imwrite" function:

https://www.mathworks.com/help/matlab/ref/imwrite.html

I hope this helps!