PDA

View Full Version : CMYK in Lightwave?



Lunar Unit
10-17-2005, 06:21 PM
I'm using Lightwave for print and the client uses CMYK. My RGB frames from Lightwave are looking pretty sorry when converted to CMYK in Photoshop. Is there a way to export to CMYK from Lightwave or any ideas on color correction in photoshop?

Panikos
10-17-2005, 06:41 PM
RGB covers a wider range of colour tones than CMYK, thats why after the conversion you get a different result.

You know, Lightwave deals with Light, so it begins with darkness, i.e black.
In Print applications you begin with white and you darken it.
For this reason, its impossible to make LW render in CMYK cause we do not begin with white and use "darkening lights" to create a result.
(LW internally renders in Full Precision and outputs 32bits per R/G/B)

An image filter could convert the rendered result in CMYK but believe me, the native Photoshop one is very mature and gives you all the control you need.

I am not 100%, but you can use the Photoshop Gamut clipping viewing option.

BeeVee
10-18-2005, 01:43 AM
In my experience, randering for eventual CMYK output requires the experience of knowing what colour combinations to avoid to reduce "muddy" looking conversions, and a lot of tweaking in CMYK to bring back the brightness. Try to steer clear of colours that need a combination of two or more of the component elements of CMYK - that's to say, greens, blues, reds that all need a combination of colours in CMYK to reproduce.

B

Lunar Unit
10-18-2005, 11:06 AM
Thanks, that certainly answers my question. I shall use these words of advice to explain the difference to my client.

Paintmonkey
10-18-2005, 09:19 PM
Usually I render in the highest res I can & save that alpha too then go into photoshop and do the conversion & check the plates to make sure separation if good for your printing method.

- See if the 64-bit RGB formats (like SGI-64) jibe with your workflow - since the 16 bpc includes more color data
- also an HDRI shader may give you some extra play when it comes to colour correcting in Photoshop. Do your CMYK conversion of the 16-BPC renders and then adjust levels according to your output devices calibration - drop that image down to 8-bits for your final layout and for compatibility sake.

Never forget to check with your printer to find out their black formula, and always double check any solid areas to be sure that they register as 0,0,0,100% - Not the muddy mixture that an RGB conversion may force upon your render.

cgolchert
10-18-2005, 09:21 PM
I'm using Lightwave for print and the client uses CMYK. My RGB frames from Lightwave are looking pretty sorry when converted to CMYK in Photoshop. Is there a way to export to CMYK from Lightwave or any ideas on color correction in photoshop?

What will the end result be? (what is it being printed on?)

Exception
10-18-2005, 10:37 PM
Do you have color management switched on and properly set up in photoshop? If not, it sure will be sorry looking... It's kinda tought to get a really ugly difference with photoshop when using the color management.. i'd look into that... post an image here so we can try it out too...

cgolchert
10-19-2005, 08:27 AM
Do you have color management switched on and properly set up in photoshop? If not, it sure will be sorry looking...

It doesn't matter cmyk always makes the colors muddy.


I asked about the end result because some printers handle RGB better than a cmyk print. The software that I've used actually prefers LAB colorspace since it is a wider gamut tha RGB or CMYK. Before it fires the print to the print it figures out what THAT printer can do, on a specific media, instead of what photoshop might think a generic profile should be.

habaņero
10-19-2005, 10:34 AM
Any decent basic introduction book on graphic design /print will give you a good boil down on how to make good CMYK outta RGB. Print aint straight forward, you should pick up a recent book on the topic, there are more than one issue you should know about.

Many printers have a prepress that will cheaply output the same as the press and so you might want to talk to the printer so as to be able to go several rounds with this, I think you'll find they are as eager as you towards the results and might not charge you much for this. It is well possible there are people at the print house that can do a better job than you on the conversion, maybe even for free as it is normal that customers become difficult when the images doesn't look like the preview on their cheap *** low quality JPEG digital cameras. I mean, my printer would tweak all images for free because of this.

If you don't have a budget I think you maybe could get better results if you output your files to dias, and have them scanned professionally to cmyk though I am not sure no the specifics or even if there would be a real benefit any longer.

I'd use the (ctrl+F5-> processsing-> image filter) PSD exporter so I could adjust layers/Z individually. Eg. particularly blue sky and blue gradients will suckalot, and so you might want to adjust your back plate separately.

As mentioned, the photoshop gamut view will reveal trouble areas before you convert and so it might be an advantage to do some colour tweaking in hdri space on the RGBs before you convert.

Now I didn't do this before myself but channels that point themselves out is specular, shadows, depth, raw colour, specular colour etc. It should be possible to isolate problems and tweak you CMYKs a lot without losing like, anything in the good areas.

Finally, don't deliver your images to the printer on five DVDs at 1200 dpi, if not requested to. Images need no more than 300 dpi for all normal uses and for final output a JPEG at highest setting is all but indistinguishable from lossless compression. I would email a 24 page magazine to my printer back in the day.

cgolchert
10-19-2005, 11:03 AM
Images need no more than 300 dpi for all normal uses and for final output a JPEG at highest setting is all but indistinguishable from lossless compression. I would email a 24 page magazine to my printer back in the day.

DON'T send any printer a jpeg. Most ask for a tiff file because it will retain all the profile crap you are fiddling around with in the beginning of the thread. Most rip software will look at that profile and figure out what you intend to do with the colors.

habaņero
10-19-2005, 12:10 PM
Well, I'd say if the printer specifically asks for a jpeg, send him a jpeg ...

I was speaking of the issue of compression affecting quality, a pdf with jpeg compression will retain profile info if you ask it too, so when I mailed the magazine I did of course include them. I got the impression the images would be output from the equivalent of Indesign. My printer always complained about the art school people that would show up with a flyer on 4 cds, that's what I was trying to make a point about.

I guess these days compressed Tiffs or maybe even PSDs is a good alternative, but some years ago these would have issues at my printer and I would certainly check with them today before sending them layered zip compressed CS2 tiffs.

cgolchert
10-19-2005, 12:29 PM
Well, I'd say if the printer specifically asks for a jpeg, send him a jpeg ...

If they ask for a jpeg, quality of your print isn't an issue for them. If you offer it to them to start with you (the client) look like you don't care what the print comes out like. jpeg is good for the web PERIOD. Don't use them. On the other end no printer should ever need anything more than a one-layer tiff unless you are wanting them to do MAJOR color matching where you are using pantone colors in specific element in the print. If it is a rendered image there is NO reason why you would deliver it in a layered format.

I'm not making this up because it sounds good, I have a large printer running four feet behind me as I type this. Unless you are doing some major tradeshow booth graphics and will have people inches away from your image there is no need to go to multiple disks unless you have multiple images... if that is the case the printer will have no problem. Also if you are having trouble fitting the file onto one cd and zipping it up helps do that. If the printer can't handle a zipped file, find another printing service because you will get jerked around with something else down the road.

habaņero
10-19-2005, 02:39 PM
Well, I know about how JPEGs are evil but still I think that there are few examples where you would be able to point out Jpeg artifacts on an image downsampled from 300 Dpi to print resolution. I mean I am speaking about at the very highest quality setting here.

My printhouse guy wasn't a craphead, I know several accomplished designers that share the judgement. If it is output on digital equipment, might be a different issue.

lardbros
10-19-2005, 02:51 PM
File sizes aren't a problem surely? A TGA zipped up will take up the same space as a JPEG!! Clever stuff! I back up all my animation stills in ZIP or RAR's and i can fit them on one DVD as opposed to 4.

kopperdrake
10-19-2005, 05:05 PM
Hmm...I regularly send highest quality jpegs to design houses as jpegs as an A2 tiff is going to be HUGE! Of course, at their end they'll invariably revert it back to a tiff to keep image size settings etc, but I hardly get involved with that end anymore. In my mind it's always best to give a client a pure RGB image if it's destined for print, as the page layout artist/graphic designer will know their printer setup far better than I can.

Your question about Lightwave outputting in CMYK has pretty much been explained - it would be impossible for Lightwave to know what printer your image is destined for, what paper it will be printed on, even the viewing conditions it's likely to be viewed under! All of these make a difference to the actual and perceived colours when you view the final image.

I use an Epson Stylus Photo 2100 to give me a basic feedback on colour reproduction - but again, this is *basic*...you can never pre-guess what the final litho print will look like. Some print houses used to supply a colour sample book for their printer, but to be honest I find it less easy to get these from them. This would allow you to convert an image to CMYK in Photoshop and then use the eyedropper tool to take spot readings of important colours (skies, logo colours etc) to see what they'd look like. Having done Cadbury work in the past I can say that Cadbury purple is one of the hardest colours to match, as is chocolate - chocolate, in my own personal colour sample book, is one step away from baby pap. Officially :)

Anyway - best thing is to set Photoshop up (if you use it) to work with one of the preset colour settings - I use Europe Prepress. This will convert it to CMYK for you, but you'll still have to fine tweak each of the channels to get them right over the important colours...blue skies are an easy one to get wrong :) It might help you to buy a book with CMYK colour swatches in as another rough guide to 'what will it look like' - I use 'Process Colour Manual' by Michael and Pat Rogondino - it has over 24,000 colour swatches of CMYK colours. It won't be 100% accurate to the printer you're likely to use in the end as it itself was printed on a particular printer, but it'll give you a good idea plus it'll teach you really quickly which colours won't print at all.

As a side issue, if your images are going to be handled by a print house then they typically work in Adobe RGB (you can set Photoshop to use this in the colour settings - the prepress settings typically use Adobe RGB as the default Work space. If you're sending your images to be printed digitally on photographic paper then set Photoshop up to work in sRGB as most photographic companies work in this (so I've been told). Makes a difference :)

Hope this helps and doesn't muddy your coloured waters ;)

Dunk

habaņero
10-19-2005, 06:23 PM
If you are gonna use the printer more than one time, it is often possible to put color tests in the areas that will be cut. leave a millimeter (or more, ask) of air though.

Just asking them what the values are for good saturated standard coulors and what will be too dark for red etc can make a big difference in adjustment.

Shouldn't be to hard to find some premade samples on the net, or make your own.

Finally, never ever send anything at all to the press that you didn't see the final proof of, all of it including the parts you checked before. Seems like simple advice, but it aint always easy to live it. Another piece of advice is to make plenty plenty of space in the schedule for reviews, adjustments and herrings in the pickle, stress is a killer.