Is it okay to edit your images in 8bit?

[charlie_draycott]

<p>I have a question. I have gotten some negatives drum scanned, They are really important images which are for my an exhibition i've got coming up. I realised that the scans were 8bit. They are 175mb tiff files so pretty large and i'd like to print them 20x24 inches. I asked the scanner guy about it as I have always been told that one should edit in 16 bit which I have always done. He assured me that it was fine. I have a retoucher working on the images also and I asked him, he also so said not to worry as he said that bits is to do with colour depth not resolution and as my images are very black (they are portraits but very dark and there is only black apart from the skin tones) and they don't really have rich colours in them that it would be fine. So I just wanted to ask what people thought? I know that it would be better to edit in 16 bit but as they're 8 will there be a noticeable difference? - i'm really worried that this could effect the image quality in the final print? </p>

[starvy]

<p>I was wondering if the bits would really make that much of a difference when you have such a large file size.</p>

[tar heel]

<p>You're dealing with people who don't care about the quality of your images. While they are correct in saying 8 bit vs 16 bit has no effect on resolution, an 8 bit image contains 16.5 million colors; a 16 bit image contains 281 TRILLION colors. Which would you prefer? Now, to be sure, no scanner can deliver that many colors, even in 16 bit mode, because the film doesn't contain that many. But scanning in 8 bit mode is definitely leaving colors and dynamic range on the table. The point of scanning in 16 bit is to be sure to capture ALL the colors and brightness gradations that exist on the film.</p>

<p>The other consideration is color gradation and dynamic range; scanning in 16 bit can potentially give you an extra 1.5 stops in dynamic range, and will most certainly give you smoother color gradations, which, in turn, will result in a higher quality print.</p>

<p>Find another lab. Especially one that doesn't argue with the customer. One reason they don't want to scan in 16 bit is that it takes so long, and resulting file sizes are very large. Always insist on 16 bit or at the very least, 14 bit scans.</p>

<p>Another thing; subsequent posts to this question will most certainly point out that very few printers print anything but 8 bit, so why scan in 16 bit mode? The Chromira lightjet printer does generate prints in 12 bit mode, and the newer high-end Canon inkjet printers accept 16 bit files (but print in 8 bit mode) and the results are astounding. In any case, scanning in 8 bit is most certainly leaving image information and dynamic range on the table, and will affect the final print quality.</p>

[mendel_leisk]

<p>Charlie, I'm guessing you thought digital darkroom would be more appropriate, so reposted. I actually thought the same thing, at least regarding Dig. Darkroom being the place for your post.</p>

<p>But, the best thing would be to ask the moderators to move your orig. post, or even just leave things as is. Most people just look at Unified View anyway, and will respond to anything that looks interesting, regardless of the forum. Posting the same question in two forums, particularly in such a short time span, will get you a mish-mash of answers, and confused responders.</p>

[sheldonnalos]

<p>Short answer is that it should be fine unless you're doing heavy tonal adjustments.</p>

<p>Editing in 8 bit vs. 16 bit doesn't affect dynamic range at all. It only affects how fine tonal gradations can be. If you have too few bits to describe a smooth gradient, then you get banding rather than a visually smooth transition.</p>

<p>8 bits already has more colors than the human eye can see, so there's not much being "left on the table" in terms of the visual difference between 8 bit and 16 bit. The 16 bit file just is more pliable for edits in post processing.</p>

<p>And yes, scanning in 16 bits is preferrable to 8 bits, but I wouldn't worry much about having your existing scans redone. As long as you edit in 16 bit and are doing just mild edits you won't notice a difference.</p>

[lachaine]

<p>Your 8-bit files are just fine for that. Don't worry about it - unless the people you have doing the work for you are totally clueless. Now, to help avoid any loss of quality every time the files are saved during this whole thing, you should of course start out with TIFF scans, not JPEGs, but the number of bits per channel won't matter. But even JPEGs will work fine if the person doing the editing does it all in one go without resaving all the time.</p>

<p>16 vs 8 bit has little to do with image quality. It has to do with the ability to do a lot of major editing without introducing visible artifacts. But in your project, if your photos need major editing like that, you've got more to worry about than the number of bits per channel.</p>

<p>For most work, bits per channel matter a lot more on internet photography forums than they do in the real world.</p>

[ejchem101]

<p>I've been wondering some of the same things charlie. I have photoshop elements 5 and in order to do any retouching I need to change to 16bit (I can do some lighting adjustment without changing though.</p>

<p>When I change it to 8bit I find it difficult to notice the difference. What should we be looking for?</p>

[tar heel]

<p>You won't notice a difference until you print the image. Especially on properly exposed portraits. Skin tones will be noticeably different.</p>

[r_johnston]

<p>Many Plugins for CS, can not even be used in 16 bit, must be used in 8bit, and they seem to do a decent job from what Ive seen. Based on what you say about your Portraits being mostly black, except for skin tones, Id say you probably could not tell the difference between 8 and 16 bit with the same images.</p>

[robert lee]

<blockquote>

<p>When I change it to 8bit I find it difficult to notice the difference. What should we be looking for?</p>

</blockquote>

<p>Working in 8 bits will get you in trouble on sections of the tonal curve that's been adjusted so it's steeper. What should be continuous tonal transition becomes discrete, i.e., banded.</p>

<p>In an image, look to large, slowly transitioning expanses like from the deep blue sky down to the horizon. Likewise, heavy adjustments to close cropped, tonally "heavy" portraiture may be problematic.</p>

[digitaldog]

<p>Ideally you’d be getting high bit scans. If you do little editing to them, they should output fine. But you’re paying for less data than the capture device could provide. See:http://www.digitalphotopro.com/gear/imaging-tech/the-bit-depth-decision.html</p>

[tar heel]

<p>Andrew, excellent article. Explains in detail what I was saying in my original post; you're leaving colors on the table working in 8-bit mode. Thanks for posting it.</p>