I tried Gigapixel on a number of images, comparing the results with similar outputs from Photoshop, On1 Resize, and Alien Skin Blow Up.
Overall, Gigapixel compares favourably, except the resulting image is darker (by about 1 stop), more saturated, and has more contrast than the original and other results (all of which are about the same). This happens regardless of whether the Enhancement check box was selected or not.
All inputs were PSD or TIFF ProPhotoRGB files, and all outputs were all TIFF ProPhotoRGB Files. As noted, I ran it with the Enhance box both selected and unselected with the same results. I also ran it for 200%, 300%, 400%, 500%, and 600% upsizing percentages - all exhibited the same behaviour.
The resizing software must not make any other modifications to the file on output … no “adjustments” please. If Gigapixel is used to resize images, additional work will have to be done to return the resulting image to its starting point in terms of exposure, saturation, and contrast - which is a fairly tough task to do without knowing how Gigapixel modified the image in the first place. Note that none of the other resizing products make any such modifications.
Please remove such processing - or at the least, identify exactly what is being done to produce the output in terms of exposure, saturation, and contrast to it can be undone … or make expose these modifications on the user interface so they can be adjusted by the user. The output exposure, saturation, and contrast need to match the input precisely unless modified by the user.
(I note that some users have experienced “desaturation” in their images … Gigapixel definitely appears to be making some unwanted adjustments at random, or possibly depending on the exposure, saturation, and/or contrast in the original. Please fix.)