Question about histogram and printing

[jammer_jammer]

<p>I'm doing some editing of scanned negatives. Even with what I would consider to be fairly minor levels tweaking, I'm ending up with histograms that concern me because of gaps that I'm seeing. These are most likely from the fact that I made the mistake of saving a lot of these scans at at compressed 8bits/channel. I do very little printing but I'm pretty sure that I've read where histograms with gaps in them could mean a problem of some sort in the prints. So, I'm turning to those of you familiar with editing and printing to share your expertise.<br>

Questions:<br>

1. Why do I see the gaps in the levels layer histogram but not in the actual histogram?<br>

2. Which histogram should I pay the most attention to?<br>

3. Based on the gaps in the levels layer histogram, would you think that there would end up being a problem with the print? If so, what would that problem be?<br>

4. If so, is there anything I can do, editing wise, to close these gaps?<br>

5. Or, is there really no reason to be concerned about this at all?<br>

Thanks for any help from those knowledgeable on this subject.</p>

<p>When I click to open up a levels layer, this is what I see:<br>

<img src="http://img716.imageshack.us/img716/7526/1levelsburntwindow.jpg" alt="" /><br>

But when I actually open up the expanded histogram, this is what I see:<br>

<img src="http://img192.imageshack.us/img192/1844/1histogramburntwindow.jpg" alt="" /><br>

Here is a small jpg of this particular image:<br>

<img src="http://img94.imageshack.us/img94/5513/1window.jpg" alt="" /></p>

[digitaldog]

<p>Since you are printing images, not Histograms, I wouldn’t get too upset. <br>

If you work in more than 8-bits per color, there will be more than enough data to overcome any such data loss in editing the image. That’s what you are seeing with the “holes” in the Histogram. Again, don’t lose sleep over it but in the future, starting with high bit data will make all the editing moot. See:<br>

http://www.digitalphotopro.com/gear/imaging-tech/the-bit-depth-decision.html</p>

[jammer_jammer]

<p>Andrew,<br>

Thank you very much. May I be so bold to ask that you or someone else, please answer questions 1-4, so that I may be better informed about those things?<br>

Thanks again!</p>

[digitaldog]

<p>1. Why do I see the gaps in the levels layer histogram but not in the actual histogram?<br />2. Which histogram should I pay the most attention to?<br />3. Based on the gaps in the levels layer histogram, would you think that there would end up being a problem with the print? If so, what would that problem be?<br />4. If so, is there anything I can do, editing wise, to close these gaps?<br />5. Or, is there really no reason to be concerned about this at all?</p>

<p>1. Because you edited the document and there’s always data loss (rounding errors).<br>

2. The main composite Histogram. <br>

3. Probably not. Its image specific and the output device plays a role too. <br>

4. No (well you could apply a big Gaussian blur and the holes would be gone, so would the image. <br>

5. Not so much and as stated, if you start with high bit data, it will never happen.</p>

[jammer_jammer]

<p>Thank you very much Rodney! The reason for concern is that I have hundreds of these images ALREADY scanned and ALREADY at 8 bits. I'm kind of freaking out thinking that I wasted a year of my life scanning and any image that I have changed levels on will print with banding. I think I'd have to shoot myself!<br>

Whew! Thanks again.</p>