CMYK issue: Krita or Cyan

[enrimoore]

sorry final note
You don't believe that 4 compare tools showing basically the same result can be right.

https://www.textcompare.org/image/  is especially effective as it shows the VERY different images

I can add that : windows, gimp , krita, all display CMYK jpg appearing identical to CMYK tiff. Good enough.
Cyan doesnt show anything since it closes down.

the mentioned textcompare tool displays more or less the actual aspect of the photos, and they are very different.

My take is simple: Gimp performs a "declared" conversion to gimp srgb, while Krita does a conversion, but
it "respects" the icc tag. Only apparently. So it seems to be working on CMYK converted files, but it absolutely is not.
Both Gimp and krita work on srgb color files. Which obviously appear and are identical.

At my age I can bet everything that CMYK converted jpg and tif files are almost totally different.
Which is the point.

So I hope some expert can suggest other compare tools to test and reach a final verdict.
Or other similar ways. But the test/s must be absolutely, fully dependable, operating at actual pixels level.

So, not really everything, but 20.000 Euros against nothing. I'll  keep my word, or bet, for sure.

Maybe it doesnt help my issue, but at least at my age perhaps I am still "awake" (can't find a word).
thanks for your help, also future, and for organizing the test/s, really

enri 

[rich2005]

Well it is a shame that you do not believe me.

Why do you not believe your own eyes ?

From one of those comparison sites you use, one that gives only 82 % similarity. They also give their difference map.

Now if you stack the images up and choose a point, can you see any difference between jpeg and tiff.  There might be some off colour compression artefacts if you look but nothing that is going to make a difference to a print.

   

Best of luck with your search. Edit -- and do not play the older and wiser card. I am probably older than you.

[enrimoore]

I am 80 in days
pity, I really wanted to clarify this thing. 
obviously I am pretty sure , say 99.8 % otherwise nonsense a bet.

I dont know about yr attachments.

"my" sites show differences not similarities
enclosed a screenshot for the shoes photo, from img2go
i created a screenshot very very clear from textcompare, but its over 2MB...

I would like to get a final verdict. Ok I am really pretty sure , but I have other 
issues with this work and anyway I am no expert so apart from those compare tools
I can't find much more

Bet for me could be on, but bet or not I don't want to force you for sure 
oh well, I got the final screenshot from textcompare, which might give an idea, even if
not quite as the other screenshot

lets see if i can send both

---

strange but i am unable to send

trying again

[Dark Allure]

Random thoughts:
I've achieved very good RGB to CMYK conversions for printers using Cyan, as a stand-alone application, in version 1.2.4, not as a GIMP plugin. From an example:

•  Approximately 76% difference between the original RGB and a CMYK *.tiff if I use the Fogra39 color profile.
  

•  Approximately 56% difference between the original RGB and a CMYK *.tiff if I use US Web SWOP v2.
  

Quite correct percentages, considering we're using different color modes and one image is intended for screens and the other for paper.

The only way I've achieved an unacceptable 99.9% difference between the original RGB and the CMYK tiff is when I use the direct export provided by GIMP 3.0 (without a plug-in). When I open the file in other programs, the tonal differences are quite large. But CURIOUS!: When I open the converted image in GIMP, whether or not you enable soft-proof, it looks great. As if GIMP had done its job well, but the other programs don't recognize it. I don't know why this happens.

Although Fogra emphasizes offset, I prefer Fogra39 over US Web SWOP v2 because it offers far fewer out-of-gamut colors. This can be confirmed within GIMP or Scribus. It also depends on your needs.

Within open source software, another great option for creating a PDF for printing is to use Scribus to generate a full CMYK:

•   Export as PDF/X1-a (if there are no gradients and/or transparencies).
  

•   Export as PDF 1.4, 1.5, or 1.6, enabling Color Management, choosing Printer (Color tab), and if bleed marks or crop marks are not needed.
  

In both cases, all images will automatically be converted to CMYK.

• If you are going to export as PDF/X-4, it forces you to convert RGB images to CMYK beforehand (with Cyan stand-alone, for example)
  

[Dark Allure]

P.D.:
Apparently, I myself found an answer to the significant tonal differences in CMYK *.tiff exports using GIMP 3.0, which I mentioned earlier:
Before exporting, you need to embed the respective ICC color profile. Go to the Image menu, activate black point compensation, and in that same menu, within Color Management, within Soft-proof Profile, choose the desired color profile (previously installed).

When exporting (Shift + Ctrl + E), select TIFF extension, in new window select Export as CMYK and select Save Color Profile.
Now, you get consistent and coherent results for printing! Good percentage of similarity 

BTW: Very possible than those differences of 93% or more, simply is because the ICC profiles are not embedded. I got much less percentage of differences