Mark, Thanks for posting. That's the first time I've witnessed anybody posting anything for examination when this topic comes up. I appreciate it. Now, in examining the images and their histograms, what I see is a lack of contrast in the 8 bit edited image relative to the 16 bit edited in the lower end. If the exact same curve adjustment operations were performed, I don't understand how this difference came about. Anyway, when I adjust the 8 bit image's curve lower end to closely match the 16 bit image curve's lower end, then the results are almost identicle. I've posted the 8 and 16 bit edited images that you posted untouced. I've also posted the adjusted (or corrected as I call it) 8 bit image. Alos, I've posted the 8 and 16 bit histograms along with the 8 bit corrected histogram. If you notice, the orginal 8 bit image has a relatively narrow range in the low end. Narrow ranges will ALWAYS lead to dull/flat looking images. The 16 bit and 8 bit corrected ranges are pretty much the same and thus, the results are pretty much the same. Navigate to http://greeraa.com/albums/bit_depth/ to see. --- mrkeene@attbi.com wrote: > Mike, > > Here is a real world comparison for you. > > http://www.pbase.com/mark_kn/16bit_vs_8bit_editing > > The image was taken with a Canon D60 in RAW mode and converted to a 16 bit > TIF. > A duplicate was made and converted to 8 bit. > An equal amount of levels were applied to both images. > The files were then resized to 640x480 for speed of loading and saved as JPG > quality 10. > No other manipulation was performed. > > Download the images (they are ~80k each). Look at the original. Notice how > far > down in the shadows the lower portion of the image is. Now observe the > Johnson > grass in the lower right foreground on the 16 bit edited file compared with > the > 8 bit edited file. Draw you own conclusions. > > Regards, > > Mark K. > > > On Tue, 21 May 2002 04:23:57 -0700 (PDT), you wrote: > > > > >Dave, > > > >Many times I preserve my images in 16 bits throughout my editing sessions > >because the theory of using 16 bits in editing sessions makes sense to my > >rational mind. But I gotta tell you, I have yet to actually see these > >differences in real pictures. MANY are very passionate about editing in 16 > >bits. They give you the reasoning. They present charts and graphs. They give > >you test cases (like color bands), instruct you to perform various editing > >functions, then tell you to evaluate the histogram to see the differences. > But > >in all my years of doing this, I have yet to have 1 person present 2 real > >pictures, one edited in 8 bits, the other in 16 bits, that actually reveals > the > >difference. It's not just me either. Dan Margulis, author of Professional > >Photoshop apparently has a standing bet. From what I've heard, he's > challenged > >anybody to produce an image that reveals the difference in the image, not in > >charts or graphs. From my understanding, nobody has done it yet. > > > >I stand ready to be convinced because the reasons to edit in 16 bits do make > >sense to me. So much so that I do edit in 16 bits many times for "just in > case" > >reasons. But until I acutally see an example of the difference, I'll never > be > >fully convinced that it matters. > > > >> > >> > >> Bob, > >> > >> Just wanted to ask a few questions regarding 16-bit editing. Are you > >> working in B&W or color (maybe both)? I've read that the main benefit of > >> 16-bit editing is in the preservation of shadow detail, but it sounds like > >> you apply it to most if not all of your images. The dumb question to ask > >> would be "Do you really see a big difference?" but obviously you do or you > >> wouldn't make the effort. So instead I'll just ask if you could maybe > make > >> a few comments describing images in which you've compared 16-bit and 8-bit > >> editing (perhaps from your original testing?) > >> > >> I haven't tried it yet with my color work in that I tend to work with > large > >> files (300 meg scans that can get very big, very fast), and I'm afraid > that > >> going to 16-bit might clog my Mac a bit. Your comments will be > >> appreciated... > >> > >> Dave Schrader > >> > >> > >> > >> > >> > >> > >> > >> > >> > >> > > > > > >===== > >Visit my digital photography web site along with a lot of other interesting > stuff at http://www.mikegreer.com. Also, Greer and Associates > (http://www.greeraa.com) offers studio photography, digital imaging services, > web site design/construction, and training. > > > >Mike Greer > > > >__________________________________________________ > >Do You Yahoo!? > >LAUNCH - Your Yahoo! Music Experience > >http://launch.yahoo.com > >- > >Turn off HTML mail features. Keep quoted material short. Use accurate > >subject lines. http://www.leben.com/lists for list instructions. > > - > Turn off HTML mail features. Keep quoted material short. Use accurate > subject lines. http://www.leben.com/lists for list instructions. ===== Visit my digital photography web site along with a lot of other interesting stuff at http://www.mikegreer.com. Also, Greer and Associates (http://www.greeraa.com) offers studio photography, digital imaging services, web site design/construction, and training. Mike Greer __________________________________________________ Do You Yahoo!? LAUNCH - Your Yahoo! Music Experience http://launch.yahoo.com - Turn off HTML mail features. Keep quoted material short. Use accurate subject lines. http://www.leben.com/lists for list instructions.