JPEG and ProPhoto RGB

[Abitconfused]

Does anyone use ProPhoto when processing JPEG images? If so, why so?

[davidedric]

If you use Lightroom, the actual processing is always done in ProPhoto (or actually a close relative, "Melissa"). What you see on the screen is another story.

Dave

[Manfred M]

I edit jpegs in whatever colour space they were taken in. Once a colour space has been assigned, there is no advantage to using a broader one as the colours have already been set and going to a wider colour space will do nothing more than remap them to the new colour space, but the boundary conditions (edges of the colour space) do not change.

ProPhoto 16-bit, is my default for raw, although if I ever were working on an image that were going to be printed on a narrower colour space (CMYK, specifically), there is a risk that the remapping will not give optimal results. This is advice I have received from photographers who did a lot of work that is printed on offset presses. This is not an issue when using inkjet printers.

Normal jpegs are 8-bit images, so there is no advantage to editing them in 16-bit. The files will be larger but the 8-bit to 16-bit conversion does nothing more than pack a string of leading "0" values, so no colour advantages.

[pnodrog]

I edit jpegs in whatever colour space they were taken in. Once a colour space has been assigned, there is no advantage to using a broader one as the colours have already been set and going to a wider colour space will do nothing more than remap them to the new colour space, but the boundary conditions (edges of the colour space) do not change.

ProPhoto 16-bit, is my default for raw, although if I ever were working on an image that were going to be printed on a narrower colour space (CMYK, specifically), there is a risk that the remapping will not give optimal results. This is advice I have received from photographers who did a lot of work that is printed on offset presses. This is not an issue when using inkjet printers.

Normal jpegs are 8-bit images, so there is no advantage to editing them in 16-bit. The files will be larger but the 8-bit to 16-bit conversion does nothing more than pack a string of leading "0" values, so no colour advantages.

Leading ?...

However I agree with Manfred that remaining in the same colour space is preferable as why risk minute colour shifts doing a conversion that will not give any benefit.

[Abitconfused]

I thought that processing in a larger color space prevented colors from going out of gamut if, for example, saturation was added.

[pnodrog]

I thought that processing in a larger color space prevented colors from going out of gamut if, for example, saturation was added.

Yes and no. Remaining in colour gamut ultimately depends on the colour space of the device the image will be viewed or printed with and is generally far smaller than Prophoto.

[Manfred M]

I thought that processing in a larger color space prevented colors from going out of gamut if, for example, saturation was added.

+1 to Paul's response. You'd have to be pushing the image very hard for this to matter and you would be likely be introducing a colour shift.

The other issue is that there are no computer screens that shows the whole ProPhoto colour space - the lower end ones are sRGB only and the more expensive wide gamut ones are around 99%+ AdobeRGB compliant. Depending on the rendering intent your computer is set to use, any OOG colours are not going to be rendered accurately as they will be remapped to whatever your screen can display. The good news is that these tend to be the very vibrant tones, so will generally not make up a significant part of the image content.

[bje07]

+1 to Paul's response. You'd have to be pushing the image very hard for this to matter and you would be likely be introducing a colour shift.

The other issue is that there are no computer screens that shows the whole ProPhoto colour space - the lower end ones are sRGB only and the more expensive wide gamut ones are around 99%+ AdobeRGB compliant. Depending on the rendering intent your computer is set to use, any OOG colours are not going to be rendered accurately as they will be remapped to whatever your screen can display. The good news is that these tend to be the very vibrant tones, so will generally not make up a significant part of the image content.

OOG = Out of the Gamut?

[Manfred M]

OOG = Out of the Gamut?

Yes, sorry - I should have spelled it out.

[Abitconfused]

I see. So if I have a printer capable of printing the Adobe RGB color space it must be complemented with a monitor capable of displaying Adobe RGB to be fully effective?

[bje07]

Yes, sorry - I should have spelled it out.

Do not apologize Manfred, it is for me the means of improving my knowledge in acronyms.

[Manfred M]

I see. So if I have a printer capable of printing the Adobe RGB color space it must be complemented with a monitor capable of displaying Adobe RGB to be fully effective?

If you wish to see the colours accurately, then I would say yes.

Carefully said, AdobeRGB was designed so that the colours on the screen would match the print capabilities of the day. This colour space is often referred to as AdobeRGB 1998, so the target was the printing technology that was used at the time. Back then much of the commercial business Adobe was trying to support used offset printing presses with the CMYK colour process. A few things have happened since then.

My fairly "bottom of the line" pro colour printer (Epson 3880) runs with nine ink cartridges, so it is capable of producing colours that are outside of the AdobeRGB colour space, yet so far as I know, there are no computer screens that can even handle 100% of the AdobeRGB colour space (although they are very close). The higher end colour printers have even more colour cartridges, so they have an even wider gamut. I use the ProPhoto colour space as my default colour space when editing raw data, so even with my wide gamut (AdobeRGB compliant) computer screen, I still get the occasional surprise when printing, especially if the image has a lot of vivid colours. I have had to tweak things a bit, relying on the printed output to guide my colour choices as my computer screen did not display them correctly.

Just as an aside, I do use a dual screen setup. My primary screen is a wide gamut AdobeRGB screen and my secondary screen is a cheaper sRGB one. I can definitely see a difference in colours, and only use my primary screen for viewing while editing.