Proper colors for print work.

Discussion in 'Design and Graphics' started by aldog, Apr 23, 2008.

  1. aldog macrumors regular

    Joined:
    Dec 12, 2007
    #1
    I'm going to be doing a poster for a local band in a couple of days here and I want to make sure that my print comes out good. I've done 2 other digital paintings of 2 local bands (note: OF, not FOR) and I wasn't 100% happy with the result from the prints, this could be partly because I rushed to get them printed, but I still think it's partly my fault.
    here are the 2 I've done...

    http://aldog.deviantart.com/art/Brobecks-Dallon-78853344

    http://aldog.deviantart.com/art/Victim-Effect-Keytars-and-Guit-77794209

    What can I do to make sure I stay within the print safe boundaries, and do you guys think that those 2 have color problems.
    thanks guys
     
  2. macsrules macrumors regular

    Joined:
    Feb 26, 2008
    #2

    I am not sure your level of color knowledge so, if what I am saying sounds really basic to you, oh well.

    A. First, history on me, I worked for a major catalog company retouching, I also went to school for Graphics/Pre-Press. This is what I got my start in, now I am doing web stuff, it is all pretty much the same. Anyway,

    1. There are two major color models, there is RGB and there is CMYK. For your purposes, before something can be printed it must be converted from RGB to CMYK.

    Why does it need to be converted?

    Glad you asked, because RGB is for viewing purposes. It is for the monitor. RGB has what is call a color space.(large one)

    What is a color space?

    These are the amount shades in each color.

    In order to print things on a normal printing press it must be convert to CMYK. These are four printing inks. I am not going to break them down because you can google that and it will tell you what each inks name.

    The CMYK color space is much smaller than the RGB color space so when the printer converts your file for printing, it finds the closes shade of that color in the new CMYK color space. Example, if a color is really bright in RGB, the closets CMYK color might be much duller if that shade is outside it's color space.

    The other problem you have is what is called DOT Gain. In short terms, you want to compensate for DOT Gain so your images are not darker when they get printed. Ink spreads.

    The best advice is to color correct in the CMYK space if, you are going to have them printed by a printer. Ask the printer about the DOT Gain and compensate for that in Photoshop. Also have the printer pull you a proof of what the final image will look like on there presses so, you can adjust your images before printing.

    As far as your images, they just look a little on the dark side, again you can compensate for that by doing the stuff above before having them printed.
     
  3. aldog thread starter macrumors regular

    Joined:
    Dec 12, 2007
    #3
    I did understand a good deal of that, but I appreciate you explaining it in basic terms, because when you got to the parts I didn't understand I would've just been baffled.
    Before converting to CMYK do I need to save my document in a particular format? Should I go with png or tiff, or would a jpg at 12 quality be ok, I just grabbed the jpg of the guitarist drawing and converted it to CMYK in photoshop and didn't notice any difference, so that's partially why I ask...is the process of converting any more than just choosing image --> mode --> CMYK?
    and then for adjusting just using the image --> adjustments accordingly?


    The part I didn't understand was compensating for DOT Gain, I'm guessing this is a bridge I can cross when and if I get to it if you don't feel like going into depth.



    Is there any purpose in not just painting in CMYK? My guess is yes there is a reason for not painting CMYK or else everyone would just do it that way...but I'll still ask.
    Thanks macsrules, that helped a lot.
     
  4. snickelfritz macrumors 65816

    snickelfritz

    Joined:
    Oct 24, 2003
    Location:
    Tucson AZ
    #4
    Many Photoshop functions are not available in CMYK mode.
     
  5. CRSpeedy macrumors newbie

    Joined:
    Feb 15, 2008
    #5
    The differences can sometimes be subtle in an image, but it can be enough to throw off the colors in your poster. I know how frustrating it can be to not be able to print that eye-catching lime green, or to print off that gorgeous panoramic mountain photo only to discover that the sky turned a shade of purple.

    In your case, yes--you're doing it right--it is simply a matter of converting from RGB to CMYK, and then going into adjustments (Selective Color is ideal for this). I usually take out around -15 to -20 magenta from my blues and add around +5 to +10 to both yellow and magenta for my reds.

    The only other thing to watch out for is brightness. The majority of the time, the image will look brighter on your screen than it will look once printed. If possible, get a small 8.5x11 version of the poster printed through the same company beforehand. That way, you can get a rough proof of how it will turn out before throwing down the big money for the large scale posters.

    Here's a quick comparison of a few of the colors being converted between RGB and CMYK:
     

    Attached Files:

  6. macsrules macrumors regular

    Joined:
    Feb 26, 2008
    #6
    aldog,


    I left out a major part that is also important to consider. Most of the screen stuff is RGB and Files are saved at 72 DPI (DPI stands for Dots Per Inch)

    What that means is the amount of detail per square.


    What we see on the screen, 72 DPI is fine, that is RGB. That captures enough detail per square for the human eye when viewing stuff on the monitor. 72 is not enough when printing high detail on the printing press.

    Print on the other hand needs to be 300 DPI. The problem you have is if you take something that is 72 DPI or you create your document in a canvas that is set to 72 DPI and then try to reset it to 300 DPI for printing (unless it is vector art). You loose a lot of information when blowing the size up. Think about it, if you have 72 items you can't just magically make them 300 items. Photoshop has to guess what information it needs to add. (this is called interpolation) You can though have 300 items and take some away to only have 72 items. That's why,

    You want to scan or create your documents that you are going to print at 300 DPI.

    There is no reason why you can't paint in CMYK but if you are going to post your images on the web too. It is better to paint in RGB at 300 DPI. When you finish, convert a copy to CMYK, color correct it. Set the Dot Gain based on the printers setting and make sure it will not go too dark. You could also have the printer pull a proof before they print.

    Then when you want a copy for the web, take the original, make another copy and scale it down to 72 DPI.


    It just means that when the printing press puts ink down it will spread and also probably go a little darker (because two of the CMYK inks make one color and they are printed on-top of each other). You won't see this on your monitor unless you compensate for this. Printers profile there presses and can tell you what to set the Dot Gain profiles in Photoshop so what you see on the screen is closer to the final product.

    Also, save the file that you will print as a Tiff. Save the file you are going to put on the web as Jpeg or GIF or PNG. Those file formats vary. Jpeg for images, Gif for Vector Art and transparence.


    snickelfritz

    You are right, if you are using a lot of the Photoshop filters, CMYK will grey out a lot of those and not let you use them.
     
  7. wongulous macrumors 6502a

    Joined:
    Dec 7, 2002
    #7
    Not to be rude, but might I suggest an evening class at a local community college to deal with vector illustration (great for print) and print design? Pantone, spot color, CMYK color space, trapping, layout brainstorming, dos and don'ts--usually an amalgam of these topics are covered. I took one a year or two ago and at $40/crhr it only ended up being about $160 and gave me way more information, ideas, and industry contacts. Plus I got to play with big MacPros with huge Wacom tablets.. :)

    It makes a lot more sense in real life explanation to some folks (me).
     
  8. aldog thread starter macrumors regular

    Joined:
    Dec 12, 2007
    #8
    ok thank you, figured there had to be some reason. I don't use any filters other than gaussian blur for the most part, but seeing as I do like to put my stuff online I'll stick with RGB

    Thanks for the examples for the adjustments you use, I assume that it won't always be the exact same for me but a starting off point is exactly what I need. I'll definitely watch out for brightness too, I think I get a little overly paranoid (as if that's possible) with that for my webbased work, even if it's just for my own collection. I'll switch between my mbp monitor and my external and sometimes even send it to my windows desktop to see how it looks.
    Thanks for teh comparison as well

    I've went through the painstaking process of scanning pictures at too low a DPI and then having to rescan them at 300 halfway through (wedding photos of my brother's) had to convince him that 600 dpi was overboard, but in all the time I've been drawing and opened a new document in photoshop I've never once thought to change the DPI setting on there, I'll definitely be painting at 300 from now on even if my original intent isn't to print, it'll be nice knowing that I can if I want to.
    Next to color mode there's '8-bit' '16-bit' '32-bit' and I've always left it on the default 8, do I need to change this as well?
    Thanks for the dotgain explanation, I understand what you mean now.
    I didn't take your advice as rude at all just so ya know. I do want to go to school for this but in due time, I know that in some cases it's much better to learn certain things in that kind of atmosphere, online and through messageboards is where I've learned pretty much everything I know about art and techniques, so that's where I decided to turn for a little (LOT) print work schooling.

    you guys are great
     
  9. macsrules macrumors regular

    Joined:
    Feb 26, 2008
    #9

    It has to do with when you are shooting images with Digital Photography mostly and how much data/color information it will hold.

    1. Example, when you shoot at 8 bits. And you down sample an image and then go back to the original (when I say down sample I am talking about color modes) you will loose some data. (remember that color spaces vary in size) Where as, if you shoot at the higher bit rate, ie 16 or even 32, the amount of data stored is more than you need and when you down sample that image (color mode) and then resample it back to the original color space you don't loose any of the color quality because it has the extra data since it is at a much higher bit.

    One thing to consider, the higher the bit rate the more hard drive space you will need.

    http://www.lynda.com has some great tutorials that talk about this and do a much better job of explaining this than I have. You also get to see the instructor take an image and down sample it and then resample it at the different bit rates.
     
  10. stainlessliquid macrumors 68000

    Joined:
    Sep 22, 2006
    #10
    Its a good idea to stay away from highly saturated colors, especially blues and reds, they dont blend well when printed. Yellows come out WAY lighter than what you see on screen. Whenever I print something that has something like a drop shadow it never comes out as "thick" as the screen, light greys tend to have the same problems as yellows where its too light against white. A printer's ability to print low contrast details in darks depends on how good the printer is, I dont think theres a way to compensate for this other than using an extremely good printer that can do very rich blacks or printing a ton of proofs until you get the right darkness (in your guitar picture Im guessing the hair came out horrible since its so dark), so if you are printing flyers on cheap paper then stay away from dark areas that have details in them.
     
  11. Kwill macrumors 68000

    Kwill

    Joined:
    Mar 10, 2003
    #11
    File preparation depends upon how the posters will be printed. How poster are printed depends upon quantity desired. Modern digital inkjet printers can have 6, 8, or up 12 inks. These are capable of reproducing a wider color gamut than traditional presses with only 4 inks.

    http://reactiveimaging.com/faq/

    Full disclosure: I work for Reactive Imaging.
     
  12. aldog thread starter macrumors regular

    Joined:
    Dec 12, 2007
    #12
    hehe, thanks for the warning kwill. even if you are promoting your site, it still looks like a good one.

    macsrules I do shoot a lot of digital photography, but going off of your explanation I don't think I need to switch any of my settings for what I do as far as that area goes, thanks for explaining.
    thanks for the lynda link, I've been on it before but I'll check it out some more.

    stainlessliquid I think most of my stuff is pretty muted in those color ranges, I'll have to stay away from printing on cheap paper though, because a lot of it has pretty dark areas that have a fair amount of detail. thanks for the tips
     

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