• Global community
    • Language:
      • Deutsch
      • English
      • Español
      • Français
      • Português
  • 日本語コミュニティ
    Dedicated community for Japanese speakers
  • 한국 커뮤니티
    Dedicated community for Korean speakers
Exit
0

Whats the ideal workflow for converting 16 bit prophoto to 8 bit srgb ?

Community Beginner ,
May 01, 2023 May 01, 2023

Copy link to clipboard

Copied

Hi,

 

I have been confused about this for a while. Would really appreciate if someone can clarify this.

 

The following are my workflows:

 

Workflow 1:

1. Edit image in 16 bit prophoto

2. Convert image to 8 bit: image->mode->8 bit

3. Convert to srgb: edit -> convert to profile -> srgb

4. File -> Save for web legacy with embed color profile and convert to srgb checked

 

Workflow 2:

1. Edit image in 16 bit prophoto

2. Image crop and resize

3. Convert image to 8 bit: image->mode->8 bit

4. Convert to srgb: edit -> convert to profile -> srgb

6. File-> save a copy 

 

Please let me know if my approaches are correct. I feel like I am over complicating it

TOPICS
Windows

Views

2.1K

Translate

Translate

Report

Report
Community guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
Adobe
LEGEND ,
May 01, 2023 May 01, 2023

Copy link to clipboard

Copied

Expect for Image crop and resize; there's really no difference.

Resize in high bit vs. 8-bit per color; sure, but I doubt that will make a difference. I'd let the conversion to 8-bit per color and then conversion to sRGB/JPEG be the last step.

Important consideration: all editing in a wide gamut color space (ProPhoto RGB) and a high bit (what Photoshop calls 16-bit). And yes, save a copy to keep the original high bit, wide gamut, high-resolution data. Spin off the sRGB/8bit per color, JPEG from that when you're ready to supply that for whatever need you have for such a document.

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

Votes

Translate

Translate

Report

Report
Community guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
Community Beginner ,
May 01, 2023 May 01, 2023

Copy link to clipboard

Copied

Thanks for you reply. So, just for my understanding, my workflow 2 is the ideal way of doing it for web?

 

Workflow 2:

1. Edit image in 16 bit prophoto

2. Image crop and resize

3. Convert image to 8 bit: image->mode->8 bit

4. Convert to srgb: edit -> convert to profile -> srgb

6. File-> save a copy -> jpeg

Votes

Translate

Translate

Report

Report
Community guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
LEGEND ,
May 01, 2023 May 01, 2023

Copy link to clipboard

Copied

What is ideal for the web is 8-bit per color JPEG (or PNG) in sRGB with an embedded profile. You can save a few steps using the Export (Quick Export as JPG), Or Export As, or manually and if all settings are equal (and that's not easy because of differing values for JPEG quality), the results would be the same.

I'm old fashioned and do this manually: resize to the number of pixels I want (say 1200x1080), convert to sRGB, Save As... JPEG.  

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

Votes

Translate

Translate

Report

Report
Community guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
Community Beginner ,
May 01, 2023 May 01, 2023

Copy link to clipboard

Copied

Thanks. Is doing image->mode->8 bit even required?

Since srgb is by default 8 bit, is this step even required?

 

I see that it's not a part of your workflow either. 

Votes

Translate

Translate

Report

Report
Community guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
LEGEND ,
May 01, 2023 May 01, 2023

Copy link to clipboard

Copied

sRGB can be any bit depth. 

JPEG has to be 8 bits per color. 

With at least Legacy Save As... you can ask for a JPEG from the original 16-bit data (after converting to sRGB) and it will convert to 8-bits per color at the same time as saving. 

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

Votes

Translate

Translate

Report

Report
Community guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
LEGEND ,
May 01, 2023 May 01, 2023

Copy link to clipboard

Copied

Now, I may be wrong, but I wouldn't favour converting to 8-bit before converting to sRGB. I'd rather do it the other way round. It seems to me that doing it 8-bit -> sRGB could increase posterization, since

(a) the conversion to 8-bit will produce at most 256 separate colours.

(b) unless it is already sRGB, the conversion to sRGB will map to fewer than 256 colours.

However, if the conversion to sRGB is first - which will reduce the up-to 32768 colours somewhat, it still seems possible that the conversion to 8-bit will produce a full range of 256 colours.

Votes

Translate

Translate

Report

Report
Community guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
LEGEND ,
May 01, 2023 May 01, 2023

Copy link to clipboard

Copied

P.S. 256 and 32768 colours is of course per channel. so it is 256^3 and 32768^3 distinct colour values.

Votes

Translate

Translate

Report

Report
Community guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
LEGEND ,
May 01, 2023 May 01, 2023

Copy link to clipboard

Copied

Indeed, safest to convert color space then bit depth last. That said, I should run a test both ways and subtract the two. And let's not forget the option to Use Dither (on/off) with such conversions. Lastly, that data will be saved as a JPEG, so even tiny difference would not be worth worrying about.

 

As for:

 

“256 and 32768 colours is of course per channel. so it is 256^3 and 32768^3 distinct colour values.”

 

Color numbers are not the same as color. Two encoded color numbers can be the same color so the two numbers can be moot:

 

http://digitaldog.net/files/ColorNumbersColorGamut.pdf

 

IMG_5301.jpeg

 

 

 

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"

Votes

Translate

Translate

Report

Report
Community guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
Community Expert ,
May 02, 2023 May 02, 2023

Copy link to clipboard

Copied

Like Digitaldog I'd do the resize manually and perhaps ad da bit of sharpening (unsharp mask) 

 

Starting with the Prophoto edited file

1: archive that edited original (with it's adjustment layers) as a master copy, full size, 16 bit, ProPhoto.

2: make a copy, convert to sRGB (probably best to do this whilst still in 16 bit)

3: resize to the right pixel dimensions for the relevant site. 

4: Unsharp mask as needed

5: Make it 8 bit

5: 'Save as' a Jpeg, I prefer'Save as' to 'save for web' or 'export'.  I like to see what's happening 

 

A note on Jpeg

Jpeg is not OK for archiving or for any file that may need to be resized or cropped down the line. 

Jpeg is the worst possible format if you want to keep high quality - you should always archive a copy of your original, with adjustment layers intact - if that’s how you work.

Jpeg compression (at any setting*) really is "lossy”, irreversible and cumulative, so should ONLY be used only for final delivery AFTER resizing & cropping to the FINAL size and crop.

Why? Any edits to size or crop, or even just re-saving a Jpeg file means further compression, potentially that’s very damaging.

The jpeg damage is not always immediately apparent, which is perhaps why it's still widely used - however, the compression will soon cause issues if you do further work and save again. That’s when you’ll see a jpeg with some real issues.

 

*don’t imagine that selecting maximum quality for your Jpeg is preserving the original data, it's still compressing a lot which discards information.

 

I hope this helps
neil barstow, colourmanagement net - adobe forum volunteer - co-author: 'getting colour right'
google me "neil barstow colourmanagement" for lots of free articles on colour management

Votes

Translate

Translate

Report

Report
Community guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
Community Beginner ,
May 02, 2023 May 02, 2023

Copy link to clipboard

Copied

Thanks for the comment! I was under the impression that srgb can only be 8 bit. I guess I was wrong. Thanks for clarifying that and also thank you for giving me the idea of workflow.

Votes

Translate

Translate

Report

Report
Community guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
Community Expert ,
May 06, 2023 May 06, 2023

Copy link to clipboard

Copied

@defaultvq8ek6mt1ouk appreciate your thanks, have a good weekend

 

I hope this helps
neil barstow, colourmanagement net - adobe forum volunteer - co-author: 'getting colour right'
google me "neil barstow colourmanagement" for lots of free articles on colour management

Votes

Translate

Translate

Report

Report
Community guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
Community Expert ,
May 07, 2023 May 07, 2023

Copy link to clipboard

Copied

LATEST

I'd look at a perceptual sRGB ICC profile  if the source image has a significantly wider gamut and details may be lost in the conversion in out of gamut areas. Standard sRGB profiles will clip OoG detail, they will use Relative Colorimetric rendering intent even if Perceptual intent is selected as they lack the Perceptual transformation table. This will potentially have more visual impact than 16 bpc vs. 8 bpc.

Votes

Translate

Translate

Report

Report
Community guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines