How to create the same png icon but with a different color?

Here is a .png of a button icon.

I need exactly the same icon, with the same style but a green color.

How can I achieve that?

RedButton

Answer 1

[Image Analyst]

Try this:

redButton = imread('red button.png');
[rows, columns, numberOfColorChannels] = size(redButton)
% Convert to Hue, saturation, value color space.
hsvImage = rgb2hsv(redButton);
% Make hue 0.3.  Adjust as needed.
hsvImage(:, :, 1) = 0.3 * ones(rows, columns);
% Go back to RGB space
greenButton = im2uint8(hsv2rgb(hsvImage));

% Display both images.
subplot(2, 1, 1);
imshow(redButton);
subplot(2, 1, 2);
imshow(greenButton);

If you want to cycle through a bunch of colors to see them all, try this:

for h = 0 : 0.05 : 1
	redButton = imread('red button.png');
	[rows, columns, numberOfColorChannels] = size(redButton)
	hsvImage = rgb2hsv(redButton);
	% Make hue the current h color.
	hsvImage(:, :, 1) = h * ones(rows, columns);
	greenButton = im2uint8(hsv2rgb(hsvImage));
	
	% Display both images.
	subplot(2, 1, 1);
	imshow(redButton);
	subplot(2, 1, 2);
	imshow(greenButton);
	drawnow
	promptMessage = sprintf('This Hue = %.2f\nDo you want to Continue, or Quit?', h);
	titleBarCaption = 'Continue?';
	buttonText = questdlg(promptMessage, titleBarCaption, 'Continue', 'Quit', 'Continue');
	if contains(buttonText, 'Quit')
		break;
	end
end

[Akbar]

Thank you very much, very interesting, I can even have other colors!

How about corners? They appear black. How to make them white or maybe transparent?

[Image Analyst]

Not sure. Just try a search: Search for PNG transparent

Answer 2

[Walter Roberson]

img = imread('ButtonRed.png');
mask = img(:,:,2) < 128;    %true for red areas but false for white areas
npix = nnz(mask);
temp = [zeros(npix,1), ones(npix,1), zeros(npix,1)];  %green
img(repmat(mask,1,1,3)) = temp;
imwrite(img, 'ButtonGreen.png');