backlit media color management

[motormount]

I'm searching for some basic - but proven - intro on this subject ,if there is any ( like i knew my way in conventional color management...)

I googled it a little bit with little luck -although i found a couple of very interesting results but not as informative as i would like.

Thanks in advance!

 

[maxon]

My two cents worth, this is an oxymoron. I don't think there's a way to control the backlight and/or ambient illumination to justify an attempt to create a color profile. But I may be wrong.

 

[rich apollo]

It can be done. Measurement is the problem. Barbieri is the only instrument manufacturer, that I'm aware of, currently building a measurement device with backlit measurement capability.

That being said, if you can get your hands on an old SpectroScan T with ProfileMaker's MeasureTool, you can read in backlit material. MeasureTool with an i1Pro can take "emissive" measurements, so you could place your test chart on a backlit surface and read in the target that way.

MeasureTool was THE BOMB! Every night before bed I pray that Xrite will bring it back.

 

[Castek]

I didn't know that MeasureTool had a mode for taking emissive measurements, I will have to look into this. Thank you for the info. There are a lot of functions in the old ProfileMaker and Monaco packages that are not in i1Profiler, and I agree that XRite should improve the feature set of i1P.

 

[motormount]

Thanks a lot.

Before spectro's and color management software, i'd like to ask if there are any kind of basic principals in terms of what kind of lighting should we choose,how ''strong'' should it be,if sticker manufactures provide any technical details for their products -like for certain thickness of the plexiglass the sticker will be applied we will need that ''amount'' of luminance etc-

I 've made a sign for a friend,in daylight color is great,but when is lit the colors are a bit ''washed out'' even though the lighting is not too strong - i would like it stronger -

To be honest,neither my friend or a couple of others who's opinion i'asked can tell the difference,but i see it, i don't like it and i don't know what should i do if i needed do another one.

If i make colors darker,then it won't look right in daylight.

Maybe it's got to do with the sticker and plexiglass transparency,but how should i know them in the first place?

Then even if i print some samples and measure them,won't the sign look different when it's raised to it's physical environment?

Thanks in advance!

 

[Correct Color]

My two cents worth, this is an oxymoron. I don't think there's a way to control the backlight and/or ambient illumination to justify an attempt to create a color profile. But I may be wrong.

You're not exactly wrong, but you're not 100% right either.

I've been making backlit profiles for clients for years, and this is something I always warn them about going in. They can't quite expect final color fidelity to be as consistent as they might with a reflective profile, just because of this issue.

However, the converse is that while the effect may be more pronounced, the color you see on a reflective piece is dependent on ambient light as well.

I 've made a sign for a friend,in daylight color is great,but when is lit the colors are a bit ''washed out'' even though the lighting is not too strong - i would like it stronger -

To be honest,neither my friend or a couple of others who's opinion i'asked can tell the difference,but i see it, i don't like it and i don't know what should i do if i needed do another one.

If i make colors darker,then it won't look right in daylight.

Maybe it's got to do with the sticker and plexiglass transparency,but how should i know them in the first place?

No, it's just a question of reflected light versus transmissive. In order to make a true backlit profile, you need a transmissive spectrophotometer, meaning one that shines light through the patches, as opposed to reflecting it off of them.

And that is the issue. Any profile-making software will make a backlit profile from the measurements. And the only difference will be the inherent differences in the engines.

Unfortunately, as Rich has pointed out, at present only one manufacturer -- Barbieri -- makes a transmissive spectrophotometer -- actually, two of them. They're fantastic machines, and they price them accordingly.

Myself, I make transmissive profiles with an ancient, rare, X-Rite DTP-41T. It's much smaller than a Barbieri, much easier to transport, and has served me well for years. It's getting a little balky now, and X-Rite no longer supports it, so I've been thinking of getting a Barbieri, but it's a big expense when there's so little call for true backlit profiles anymore because you're right...

You can't have it both ways. If you make a correct, true, backlit profile, it's going to look great lit, and too dark unlit. That's just the nature of the beast and something you need to be able to explain to clients if you can offer them true backlit.

It is possible to make mid-backlit, by reading a transmissive set of patches, and then a reflective set, then averaging them together and making a profile from the result. I've done it for clients before and done correctly it works surprisingly well.

But...

The best way to do backlit is some combination of color-white-color.

Done this way, a frontlit profile can be used, and the image looks great frontlit or backlit.

And what I'm thinking is that as this becomes more and more common, less and less people will have a need for true backlit profiles.


Mike Adams
Correct Color

 

[motormount]

Mike thanks a lot - although i didn't quite understood the color -white -color option,is that you apply two stickers one in front and one behind the plexiglass?
-But then you might face ''registration'' problems.-


This is the sign,it's an illustration i did for a friend of mine.

I thought it a lot cause i wasn't really happy with the result,and i concluded that when it comes to photos and illustrations,backlit might not be the best way to light the sign,external lighting might be better.
Backlit may be better for ''vectorish'' signs -letters only etc where there are usually two or three solid and striking colors,and not subtle tones as a photo or a sketch might have.

I know it's not a very ''flexible'' approach to the subject, but i couldn't come up with anything better.

So if you could explain the color - white -color concept i might do better next time!

Thanks again!

 

[Correct Color]

Well anything looks great backlit as long as it's lit.

I've got one client who does fine art aqueous backlits that are breathtakingly gorgeous, and they're always photographic images. But of course they're never meant to be viewed without the back light.

Same with airport backlits and backlit menus and the like.

Color white color is any process where you have the color image, then a translucent white layer, and then the color image again.

You can do it front and back on a translucent sheet -- many flax-face signs are made this way on grand format printers -- and you're right, the key is registration.

The most common way these days though is on a UV printer, all in one pass, all on one side: Color, then white, then color. The quality isn't up to fine art, but for most signage, the result is really striking.

For your image here, you'd do it all on transparent adhesive vinyl, then mount that to clear plexiglass.

Looking at your image though, I think if it was me, I'd want to do that to a very high almost fine-art quality level. In which case I'd do a true backlit, explain what it is to the client, and explain they have to leave it lit for true effect.

I can't imagine they wouldn't love it.

What kind of printer/RIP setup are you using?




Mike

 

[motormount]

What kind of printer/RIP setup are you using?

I don't have anything to do with sign making - i'm doing the prepress among other things for a sheetfeed printer -,this was done for a friend of mine, but like i said i wasn't satisfied and i'm asking all this just in case something similar comes up.

You wrote that you would do this in a ''a very high almost fine-art quality level''

You mean 300ppi physical size,or a little smaller ?

This is a 1.2*2 meter sign - something like 3.5*6 feet i think,which hangs 6 feet from the ground as well.

The digital printer i asked how he wanted the file told me a cmyk file,stripped from all profiles at 100ppi in natural size.

It doesn't look very good when you look it just bellow the sign,but this is supposed to be seen from a much greater distance.

What kind of file would you suggest i should prepare?

And what kind of lighting inside the sign?

Thanks again for your time!

 

[Correct Color]

This is a 1.2*2 meter sign - something like 3.5*6 feet i think,which hangs 6 feet from the ground as well.

The digital printer i asked how he wanted the file told me a cmyk file,stripped from all profiles at 100ppi in natural size.

It doesn't look very good when you look it just bellow the sign,but this is supposed to be seen from a much greater distance.

What kind of file would you suggest i should prepare?

And what kind of lighting inside the sign?

Ohhhhhhh...

I assumed you were printing the thing.

Since you're not, it's not up to you to apply any kind of final printer profile.

And what I meant by "fine-art" had more to do with the printing process. But it does depend on where the thing is going to be used, and viewing distance.

If it's going to be viewed indoors, up close, I'd want to use an aqueous printer, use a translucent material that would hold lots of ink, and use a true backlit profile.

If it's going to be viewed outdoors and from a distance, then color-white-color on some sort of UV printer would get the best overall result.

As to what kind of file, it sort of depends on what you've got to work with. But, what your printer asked for should absolutely never be done. You always want to tag your file with the color space in which you created it.

Most times in large format, you want an RGB file, always tagged; working in and tagged as Adobe 1998 if you build it yourself, most likely sRGB if you did not, and then the RIP should convert it to the final printer space at print time.

And the final printer space means a custom profile, made for the printer on that material in that environment. This is where a backlit profile would be applied.

As far as the lights inside, honestly, that's the least of your worries. If you get everything else correct, you'll love the result.




Mike

 

[motormount]

Most times in large format, you want an RGB file, always tagged; working in and tagged as Adobe 1998 if you build it yourself, most likely sRGB if you did not, and then the RIP should convert it to the final printer space at print time.





Mike

That's what i had in mind,but the printer wanted a cmyk file.

To be honest,i gave him a card with almost the same artwork,and the sticker colors in daylight are almost identical to the offset printed card.

Thanks again for your time,and for your site's link,it's a bookmark!

 

[rich apollo]

The digital printer i asked how he wanted the file told me a cmyk file,stripped from all profiles at 100ppi in natural size.

I will agree with Mike. This is the way not to do it.

You have been coerced into committing "color crime".

 

[motormount]

I will agree with Mike. This is the way not to do it.

You have been coerced into committing "color crime".

( crime pays,more than prepress at least )

Theoretically you're right,but like i said the sticker ( backlit paper ) was printed amazingly close to a business offset printed card i've made for my friend with similar artwork and same colors, so no problem with that.

I would like to ask another question now.

I rarely touch photoshop anymore,don't need it in printshop i work,and all my parttime photography i do is edited in lightroom.

I'm aware of rgb workflows in theory only, cause all the years i was working in ateliers, we were editing mainly cmyk.

So here's the question:

If i give an rgb photo with minor editing/almost straight out of the camera to the printer tagged with even a pro photo rgb profile with a deep violet sky, or a nice red ferrari with all the reflectors hues,what should i expect?

I assume that i should be working in photoshop in proof colors mode,but then what's better will the in rip separation will provide me -apart from a lighter file- ?

Thanks in advance!

 

[Correct Color]

Well, the problem is that crime always pays...

until it doesn't.

If i give an rgb photo with minor editing/almost straight out of the camera to the printer tagged with even a pro photo rgb profile with a deep violet sky, or a nice red ferrari with all the reflectors hues,what should i expect?

What you should expect is for the printer to understand color management and to be able to get the best possible print out of your image; to get as close as possible to the original image, even if some/many of the colors are out of gamut.

And that means working the file -- in whatever editing program you choose -- in an rgb working space that doesn't cut color out of the image, and then converting it to whatever its final print destination is at print time, and not before. And yes, it is ideal to have the final print profile available for soft proofing.

What your printer did was attempt to subvert the entire color management process, no doubt by passing your cmyk numbers through his RIP unaltered, no doubt thinking he was keeping color intact because he kept the cmyk values intact.

But that's not the way it works.

You may like the way that particular image turned out, although I'll point out it is not a match in its properly lit condition, but if you'd had specific colors to match in the image, say a corporate color in the red, or a specific BMW blue, you would have absolutely no way except trial and error to get there.


Mike

 

[mscotty]

We are producing a lot of backlit with HP latex, no problem at all, we have started with some HP profile and worked just with linearization curves (in Caldera RIP) to achieve best result.

One of our customers before contacting us had some bad experience with backlit prints, that looked washed (actually he called it - milky). In my experience it was just some operator didn’t applied high-dense print regime.

Maybe if you write your set up (printer+rip) someone could help...

 

[motormount]

Mike,the procedure you describe is what i did back in my service bureau days,respecting file profiles edit them in whatever color space suitable for the file needs but we did the converting to destination in photoshop, not our rip.

In most printing houses i know,digital or offset,lack of knowledge or time - or both - doesn't allow such file treatment.

At least for me a lot of times i can't keep up even with well prepared files - and i'm talking strictly pdf's - and that's like a 20% of the files i get.

I'm the single prepress person here - like in most printshops i know - but lately i was talking to an old colleague of mine, still working at a service bureau which evolved to a decent digital printer -couple of indigo's, some large format printers and lots of postpress work.

Even there,were is enough manpower with heavy prepress experience, files get only the absolutely necessary editing, bleeds,overprints etc.

Color corrections are performed only when there is a serious problem (heavy color cast's etc ) and only after the clients approval for the pricing.

And yes,trial and error method - as i understood by contextual saying- is no stranger to them either.

I'm writing all the above, not because i approve such practices but to point out that -unfortunately- that's common practice for the majority of shops i know, and i wouldn't trust a printshop to color edit my files, more over to hand them an out of gamut rgb photo and expect them to get it printed fine.

Another one

The color-white-color method,is it suitable for vinyl too?

-The sign was printed on vinyl then mounted on plexiglass-


@mscotty,
thanks, i'm no digital printer, only did a sign for a friend, if you read above you'll see!

 

[Correct Color]

The color-white-color method,is it suitable for vinyl too?

-The sign was printed on vinyl then mounted on plexiglass-

Yes. That's a pretty typical application. Print color-white-color on clear self-adhesive vinyl, then mount the image to clear plexiglass.


Mike