Stephen writes ... > On 2/8/03 16:51, "michael shaffer" > > >> (1) create a copy of the JPEG file. > >> (2) open the copy ... assign AdobeRGB, add copyright and save. > >> (3) compare file sizes > >> (4) verify RGB loss by comparinging both images as "differenced layers" > > > > > I remember this being used before to check for differences in data but > cannot find it in my saved mails, do you mind taking me through the steps, > is it to place on copy over the other while holding shift to align them , > then make one layer "difference" but what then, how do you compare the > files?
(1) assuming you have 2 identical copies, open them both. (2) make the changes to one, save (not save as) & close (you need to open it again because PS will not show any artifacts with the origial). (3) open the saved file, select all and copy (4) paste into origial image (it will become a layer) (5) dbl-clik the layer, and apply as difference (the image will become black) (6) merge the layers (careful not to save, overwriting the original) (7) open the levels dialog, and squash the histogram to reveal any pixel values near '0' ... if any pixels brighten, then there were differences. Alternatively, you can use image=>calculations (subtract) and put differences into a new image. hth & cheerios ... shAf :o) Avalon Peninsula, Newfoundland www.micro-investigations.com (in progress) =============================================================== GO TO http://www.prodig.org for ~ GUIDELINES ~ un/SUBSCRIBING ~ ITEMS for SALE
