Re: CMYK JPEG (Warning large file size - 600KB)

Tim Morrison wrote:
> 
> Tim Morrison wrote:
> 
> > the CMYK version is 675 KB...
> 
> This is the CMYK one. Looks OK if opened in something that understands
> CMYK, like Photoshop or Photo-Paint, but pretty dreadful in anything
> else.

I don't understand the last sentence. Surely all that is needed
is the ability to use an embedded profile to convert from the
CMYK color space used in the file to the RGB working space used
in PSP. The fact that PSP cannot edit in a CMYK working space
(i.e. "understand" CMYK) is not significant. Have I misunderstood
what you are saying?

Alfred wrote:
> 
> The conversion from CMYK to RGB might cause severe color shifts in an
> application that is not able to show CMYK files as you noticed in your
> display example.

Well it might, but I don't see why it should. What is the
point of a color profile if not to guide the color space
conversion in a way that minimizes visual color differences?

> When opening the file in Photo-Paint, there are no color
> shifts when compared to the sRGB version.

Yes, that would be my expectation (at least roughly).
However, this doesn't require the image to exist as a
four-channel image or the app to support four-color
editing (i.e. a CMYK working space). An three-color
RGB image would work just as well. The phosphors in the
display (or the color filters in an LCD) are red, green
and blue anyway.

I have a suspicion that in the case of PSP the file format
library might be doing something evil when reading things
like CMYK TIFF or JPEG, such as using some built-in conversion
rather than the color profile or using the profile incorrectly.
Of course that's only pure speculation and would have to be
tested carefully (or, less probably, explained by Corel).

> The one thing that is unusual is
> that Tim has embedded a CMYK profile, since CMYK profiles are depending on
> the printing press, there is no sense of embedding a profile that can't be
> used.

Exactly.

> Corel Photo-Paint does not allow the embedding of CMYK profiles in to
> JPG files!

That's why Photoshop is considered to have more functionality :)

The conversion from CMYK to RGB might cause severe color shifts in an 
application that is not able to show CMYK files as you noticed in your 
display example. When opening the file in Photo-Paint, there are no color 
shifts when compared to the sRGB version. The one thing that is unusual is 
that Tim has embedded a CMYK profile, since CMYK profiles are depending on 
the printing press, there is no sense of embedding a profile that can't be 
used. Corel Photo-Paint does not allow the embedding of CMYK profiles in to 
JPG files!
-- 
Jewelry By Alfred
www.alfredky.com
"Spandex Rutabaga" <SpRu@agabatur.xednaps> wrote in message 
news:47E88397.5D788233@agabatur.xednaps...
>
> Tim Morrison wrote:
>>
>> Tim Morrison wrote:
>>
>> > the CMYK version is 675 KB...
>>
>> This is the CMYK one. Looks OK if opened in something that understands
>> CMYK, like Photoshop or Photo-Paint, but pretty dreadful in anything
>> else.
>
> I don't understand the last sentence. Surely all that is needed
> is the ability to use an embedded profile to convert from the
> CMYK color space used in the file to the RGB working space used
> in PSP. The fact that PSP cannot edit in a CMYK working space
> (i.e. "understand" CMYK) is not significant. Have I
misunderstood
> what you are saying?
> 

-- 
Jewelry By Alfred
www.alfredky.com
"Spandex Rutabaga" <SpRu@agabatur.xednaps> wrote in message 
news:47E900E3.BBF54159@agabatur.xednaps...
>
> That's why Photoshop is considered to have more functionality :)
>
And those functionalities get readily abused :) 

Alfred wrote:
> 
> --
> Jewelry By Alfred
> www.alfredky.com
> "Spandex Rutabaga" <SpRu@agabatur.xednaps> wrote in
message
> news:47E900E3.BBF54159@agabatur.xednaps...
> >
> > That's why Photoshop is considered to have more functionality :)
> >
> And those functionalities get readily abused :)

Readily and expensively - no dispute there.