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Author Topic: 8-bit vs 16-bit, sRGB vs other, etc.  (Read 3051 times)
zombywoof
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« on: July 22, 2011, 07:23:06 PM »
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I am relatively new to Photoshop, and am planning on working on some images (from .jpgs and RAW files) which I will ultimately have printed with a mail order lab like Mpix.  

They ask for 8-bit, sRGB .jpgs...is there any reason to work on the files with other ("better"?) settings (16-bit, ProPhoto RGB, etc.) before exporting them, or would it actually be best to stick to 8-bit/sRGB all the way through?

Thanks.
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Alan Goldhammer
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« Reply #1 on: July 22, 2011, 07:53:31 PM »
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Stay 16 bit until the final conversion.  Once you discard data, it's gone forever and cannot be retrieved.  Always shoot RAW for the same reason and do your manipulations on the RAW files.  ProPhoto is the defacto workspace because of the wide color gamut and again you want to have this available even if you are ultimately converting to 8 bit, RGB, JPGs.  You may end up purchasing a good printer one day and you will want the best images possible to print out.
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NikoJorj
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« Reply #2 on: July 23, 2011, 07:18:23 AM »
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Ditto : start from the richest data (raw), work in the larger space available (ProPhoto) with good precision (16bits), and compress information (sRGB, 8 bits) at the latest possible moment : only at the end of the workflow while saving your jpeg.

Editing a jpeg can be fine sometimes, but if you have to push the cursors, it could be not that fine.
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Nicolas from Grenoble
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Sareesh Sudhakaran
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« Reply #3 on: July 23, 2011, 11:18:04 AM »
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In an ideal world you should work in 32-bit (float). However, most of the effects in Photoshop don't work in 32-bit mode, and if you scale down to 16-bit, there will still be some effects that don't work. If your files have heavy effects, stick to 16-bit or 8-bit as long as the effect is available in that color depth. Otherwise, stick to 32-bit until the final render, which is 8-bit. Just to be clear: 16-bit is good enough for printing.

sRGB is the color space all computer LCD monitors use. It's not the only option, but if that's how your files are going to end up, it's best to work in sRGB right from the word go, and calibrate your monitors for the same.
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« Reply #4 on: July 23, 2011, 12:55:10 PM »
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sRGB is the color space all computer LCD monitors use. It's not the only option, but if that's how your files are going to end up, it's best to work in sRGB right from the word go, and calibrate your monitors for the same.

Actually, no...my displays cover 98% of Adobe RGB. A lot of photographers are using wide gamuts displays. But using sRGB for editing is not optimal since shooting in raw and converting to sRGB will actually result in clipped colors your camera can capture but that can't be contained in sRGB. ProPhoto RGB is the only colorspace that won't clip any colors your camera can capture.

Not sure why you think working in 32bit is optimal either...other than HDR, 32bit won't buy you any more range from a single image.

To the OP, it's optimal to work in 16 bit ProPhoto RGB up to the point where you have to prepare the deliverable file. Then flatten, convert to sRGB (if that's what the lab demands, better to try to get a printer profile) then convert to 8 bit.
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bjanes
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« Reply #5 on: July 24, 2011, 07:53:24 AM »
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But using sRGB for editing is not optimal since shooting in raw and converting to sRGB will actually result in clipped colors your camera can capture but that can't be contained in sRGB. ProPhoto RGB is the only colorspace that won't clip any colors your camera can capture.

To the OP, it's optimal to work in 16 bit ProPhoto RGB up to the point where you have to prepare the deliverable file. Then flatten, convert to sRGB (if that's what the lab demands, better to try to get a printer profile) then convert to 8 bit.

As Jeff has pointed out, 16 bit ProPhotoRGB is the optimal working space, at least for experienced users. However, you have to be careful in your editing, as you can easily push saturation to levels that can't be displayed on screen or printed and severe clipping can occur.

sRGB is not the native space of any printer, and those that request sRGB convert the image to the printer's working space. sRGB is not that bad of a choice for laser printers that print on photographic paper, as it contains most of the colors that can be printed. See the 3D gamut plot from Drycreek.com for the Fuji Frontier printer using Crystal Archive paper. Only a few high luminance yellows would be clipped from sRGB. However, there is a gamut mismatch and sRGB contains many colors that are out of the printer's gamut and these can be clipped.
 
It is much better to have a profile for the printer that you will be using, and the better labs can supply their profile. Costco does have custom profiles for their printers at Drycreek.com. Having a profile will allow you to soft proof in Photoshop and other more advanced photo editing software, and will allow you to choose a rendering intent, usually colorimetric but perceptual is useful in some cases. Perceptual rendering is not available for the sRGB space, even though Photoshop does not gray out that option. See the tutorial on Drycreek for some basic information. The late much lamented Bruce Fraser has posted a good tutorial on rendering intents. One pearl that I learned from reviewing the tutorial that saving JPEGs with the Optimized Baseline format will yield a smaller file in many cases and give better color. The Standard Baseline is the default in Photoshop.

If you prefer to work in 8 bit sRGB and use ACR, it is best to do all editing in ACR, which uses 16 bit internal processing. Editing an 8 bit file will result in data loss. If the gamut of your shot exceeds that of sRGB, you will see clipping on the ACR histogram. If there is no clipping, the use of a wider space has no advantage and can result in posterization of an 8 bit file.

Regards,

Bill



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digitaldog
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« Reply #6 on: July 24, 2011, 11:27:04 AM »
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However, you have to be careful in your editing, as you can easily push saturation to levels that can't be displayed on screen or printed and severe clipping can occur.

Exactly. One tip is that as you edit images, say moving the Saturation or Vibrance sliders, when you get to a point that you no longer see anything updating on-screen as you move the sliders, you probably want to back off and stop adjusting! The numbers are changing, you can’t see it. Danger Will Robinson.

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It is much better to have a profile for the printer that you will be using, and the better labs can supply their profile.


Yup, a message we still seem to be vocal about nearly 13 years after Photoshop 5 put color management on the map.
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Andrew Rodney
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