How to validate contrast adjusting using imadjust comparing to other contrast adjusting techniques and original image?

I want to compare the difference between imadjust image and original image using a specific measurement o technique.Can you suggest any technique to show the differnce between original and imadjust image?

Answer 1

[Image Analyst]

You can cast the images to double then subtract them to see the differences

diffImage = double(image1) - double(image2);
imshow(diffImage, []);
impixelinfo;

You can also view the values in the workspace/variable inspector - just double-click on the variable name in the workspace panel.

[Nayana R]

Thank youfor your answer Image Analyst.

[Nayana R]

Can you suggest any other method to show the difference using a value of a graph?

Answer 2

[DGM]

The question and comments are vague, but this is my answer to one interpretation -- i.e. to use a graph to illustrate the transformation made to the image data. Consider a simple gamma adjustment. We should see a simple power function.

inpict = imread('tire.tif'); % original
outpict = imadjust(inpict,[0 1],[0 1],0.5); % adjusted

[xx idx] = sort(im2double(inpict(:)));
yy = im2double(outpict(idx));
plot([0 1],[0 1],':','color',[1 1 1]*0.5); hold on % reference line
plot(xx,yy) % the TF curve
xlim([0 1]); ylim([0 1])
axis square
grid on

Note that you'll only be able to draw the curve over the range represented by the images. Consider an image with a much lower dynamic range.

inpict = imread('pout.tif'); % original
outpict = imadjust(inpict,[0 1],[0 1],0.5); % adjusted

[xx idx] = sort(im2double(inpict(:)));
yy = im2double(outpict(idx));
plot([0 1],[0 1],':','color',[1 1 1]*0.5); hold on % reference line
plot(xx,yy) % the TF curve
xlim([0 1]); ylim([0 1])
axis square
grid on