Screenshot brightness/dynamic range on Retina Display

I’m having some issues with screenshots and project that is overlaying lots of layers with low alpha.

in this image, the left side is how it displays using the compiled application, and the right side is the screenshot.

I’m Using the following code for a screenshot.

if ( key == OF_KEY_RETURN ) {
        img.grabScreen(0, 0 , ofGetWidth(), ofGetHeight());"screenshot.png");

Is there a setting somewhere to account for dynamic range, or does anyone have any idea what might be causing this compression?


I believe I just solved my own problem, saving as PNG saved with a transparency, and the white parts of the image were being rendered as layers of transparency. Saving to .jpg solved this problem, evidently it auto-detects what file format to save by the file extension.