New HP L 25500 colour peculiarity question

[Ian Stewart-Koster]

After umpteen head cleanings, I'm happy with the shades of red/orange/yellow that the L25500 is printing.
Ditto with the blues.

Here is the odd thing:

I make a box in Corel - X3 or X5 - no difference, in CMKY.
Fill it with Corel process blue straight off the color menu - which equals cyan.
Export it as a jpg, with whatever default profiles are in Corel.

Import that jpg back and pit it beside the original box - they look the same on the monitor.
Save the whole file as a PDF, open in Onyx Prod'n House, and RIP it.
Now it matters not at all whether I turn all profiles off, or leave all on, or any of the variants on offer.

The box that was the blue jpg reimported then sent as a PDF prints true to the colour expected - the box that was the correct colour but exported only from a vector to PDF, is washed out and much paler- a turquoisey aqua colour.

Other primary colours are not affected this way - only the blues. The greens are tolerably identical whether Vector to PDF or vector to JPG to PDF.

Any ideas why the vector to PDF comes out wrongly?

Thanks!

 

[ikarasu]

Open both files up in onyx, Click color correction, tools, sample point, and see if the CMYK files in "Before" Match on both, and in "after" if profiles are turned on, match in both.

I don't use corel, so I can't help you there. but I have a feeling whatever you're doing, is saving the CMYK values as something differently.

Maybe one way is saving it as RGB or something? (Again, shot in the dark, We use Adobe)

 

[Ian Stewart-Koster]

Open both files up in onyx, Click color correction, tools, sample point, and see if the CMYK files in "Before" Match on both, and in "after" if profiles are turned on, match in both.

I don't use corel, so I can't help you there. but I have a feeling whatever you're doing, is saving the CMYK values as something differently.

Maybe one way is saving it as RGB or something? (Again, shot in the dark, We use Adobe)

Thanks - but they're both in the one file - as I said I imported the JPG back into Corel Draw, then saved the whole lot as a PDF.
I originally did it with lots of boxes of known and frequently used colours - but the cyan/process blue is the only come to come out woefully different from the original file.

 

[richsweeney]

Thanks - but they're both in the one file - as I said I imported the JPG back into Corel Draw, then saved the whole lot as a PDF.
I originally did it with lots of boxes of known and frequently used colours - but the cyan/process blue is the only come to come out woefully different from the original file.

I suspect the problem is the jpeg conversion. I think every translation is going to change it from your original.

 

[Christian @ 2CT Media]

You said in your post what the problem is. You have raster data and vector data in the same file, by default corels rendering intent is set differently for raster and vectors. If you save a file with both side by side it's going to translate each element differently.

 

[Ian Stewart-Koster]

I suspect the problem is the jpeg conversion. I think every translation is going to change it from your original.

Rich, and 2CT, - thanks - but the raster or JPG is converting very accurately - it's the vector that is not!
That's got me stumped, as I'd have expected the vectors to be 'purer' or truer.

I would not be expecting to have to take all Corel files, save as a jpg, then RIP from that, when I can just rip from a PDF of the vector as a much smaller file,
except the JPG blues in the PDF are accurate and the same vector blues in the PDF are not.
(but on the monitor they look the same)

 

[Christian @ 2CT Media]

Rich, and 2CT, - thanks - but the raster or JPG is converting very accurately - it's the vector that is not!
That's got me stumped, as I'd have expected the vectors to be 'purer' or truer.

I would not be expecting to have to take all Corel files, save as a jpg, then RIP from that, when I can just rip from a PDF of the vector as a much smaller file,
except the JPG blues in the PDF are accurate and the same vector blues in the PDF are not.
(but on the monitor they look the same)

You didnt read what I told you, your rendering settings in Onyx are not the same between vectors and raster. Rendering Intents When you work with files that contain both you will have to make sure that the rendering profile is the same on both. If you turn all profiles off Onyx defaults to perceptual for raster and saturation for vectors.

 

[Ian Stewart-Koster]

Thank you again, 2CT - I did read it - but I could not find where to do the eyedropper test etc.
(I'm a brushie signwriter since the 1980s, and know the ins and outs of plotters and cnc systems, but am very new to RIPs and owning a digital printer, that's all)

Thanks for your link above - I'm checking it out now.
(I apologise for any perceived ignorance on my part!)

However, I did a lot of test prints of different coloured boxes, all exported as a JPG then reimported into the same Corel file and put beneath their corresponding vector 'mother'. Some I printed with all ICC profiles in Onyx turned off, in Onyx, some with all ICC on, and some with selected versions chosen. And Off, or on, the vector blue was still wrong, while most other colours showed not a huge difference - or not a difference that would get me into trouble if used. Some were a bit more saturated, some were a bit washed out, but the vector versus jpg colours were only 1 or 2% visually different - and the difference was mostly tolerable. The blues differences were miles off-beam.

 

[Christian @ 2CT Media]

Thank you again, 2CT - I did read it - but I could not find where to do the eyedropper test etc.
(I'm a brushie signwriter since the 1980s, and know the ins and outs of plotters and cnc systems, but am very new to RIPs and owning a digital printer, that's all)

Thanks for your link above - I'm checking it out now.
(I apologise for any perceived ignorance on my part!)

However, I did a lot of test prints of different coloured boxes, all exported as a JPG then reimported into the same Corel file and put beneath their corresponding vector 'mother'. Some I printed with all ICC profiles in Onyx turned off, in Onyx, some with all ICC on, and some with selected versions chosen. And Off, or on, the vector blue was still wrong, while most other colours showed not a huge difference - or not a difference that would get me into trouble if used. Some were a bit more saturated, some were a bit washed out, but the vector versus jpg colours were only 1 or 2% visually different - and the difference was mostly tolerable. The blues differences were miles off-beam.

Sorry I wasn't trying to come off crummy... what you are describing is what happens when Onyx has 2 different rendering intents. Its translating the same colors differently Which means that Say CMYK 100, 80, 20, 30 stays the same in raster but converts to 90, 85, 10, 45 in Vector... it all depends on what the intent is and how it will render.

 

[Ian Stewart-Koster]

Thanks - I'm understanding what you're saying now!

I've been trying to upload a pic of what I mean - but having problems- I keep getting error messages- so I''ll try a different way, and link a pic.|

You can see most colours are similar between the top row (vector to PDF) and the 2nd row (vector to jpg, reimported, then to PDF. But the Corel cyan pms306 is a vastly different colour, regardless of whether I had all ICC profiles off in Onyx job creator (top photo) or all ICC profiles turned on (bottom pic).

 

[Christian @ 2CT Media]

All profiles off defaults to 2 different rendering intents in Onyx and it looks like your ICC profiles are also going to 2 different intents.

 

[ikarasu]

Thanks - I'm understanding what you're saying now!

I've been trying to upload a pic of what I mean - but having problems- I keep getting error messages- so I''ll try a different way, and link a pic.|

You can see most colours are similar between the top row (vector to PDF) and the 2nd row (vector to jpg, reimported, then to PDF. But the Corel cyan pms306 is a vastly different colour, regardless of whether I had all ICC profiles off in Onyx job creator (top photo) or all ICC profiles turned on (bottom pic).

Rendering intent is a little different than ICC profiles. Go to Job editor for your image, Turn profiles on... Click change profiles, Click Rendering intents, and make sure CMYK and vector are the same.

That COULD be the problem, but unless you went fiddling with the intents, I don't think it is. If it's different... change them to the same and try again. If you want to upload the problematic file somewhere, or e-mail it (lucidify at gmail.com) I'll open it in onyx and see if it's doing something funky.

 

[Ian Stewart-Koster]

Thanks - I checked intents- and both types were set for the same - perceptual.
I've not had time to study the Onyx manual, and have to get on with some other commitments at the moment, but I've also just emailed the file to you, in case anything weird jumps out as blindingly obvious to you!
Many thanks again!
Ian

 

[ikarasu]

The CMYK Values of the JPG and the Vector are different, so it's not an onyx issue.

Cyan 306C has a Value of - 73,4,7,0. In your jpeg import, it has a value of - 100,0,0,0. Which will obviously make it much more blue.

Every color in the jpg is off - 102C Yellow is just 100% pure yellow value also. The others aren't too far off.. but I can notice the color change on my monitor (My monitor is calibrated with a specto. yours may not be).

I re-traced your steps... I exported the whole thing to JPG, re-imported it, and the CMYK values stayed the same for me. So it must be something you're doing when you export... Have you tried to re-trace your steps and see if it comes out the same? You can always take the little eye dropper in corel and compare values.

Thats why the colors are different when printing - Something is going on with your corel exporting.

Now... your 306C shouldn't look green like that. Does your printer have custom profiles, or are you using downloaded ones, or just always printing with profiles off?