hisoka SG A question about image processing/analysis i came across. how to tell if an image is grayscale or colour. any ideas? the image is given in a pdf. or jsut a generic image. of course i guess if it was in a compressed format then we can just query the compression format and values. edit: add in question on feedback from eagle
eagle SG this question hor, should be asked to ndmmsmallant I didn't take any modules in image processing techniques Finally, I don't see any question except "any ideas?"
ndmmxiaomayi SG Not too sure how to tell.. but as far as I know, any file that is converted to PDF is most likely intact... that means there's no change in colours or whatever. Unless it has been purposely converted to greyscale... That will need an image processing program to find out if it has been edited before. US do this a lot... I can't find the Blackhat presentation on it.
hisoka SG hmmz, so is look at the coding of the pdf to find out arh? any ideas if say given an image find out if grayscale or colour?
ndmmxiaomayi SG Probably not directly as a PDF file. The image will need to be extracted out. If it's greyscale, in a hex editor, it's nearly all 0 or Fs. Grey is derived from black... so as it goes lighter, Fs are added. A hex editor will help.
eagle SG if you have the image open with adobe photoshop Go image-> mode you will see whether it is RGB or grayscale
