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Photoshop ppi and dpi ?

Discussion in 'Adobe' started by signguy95, Apr 20, 2005.

  1. signguy95

    signguy95 Active Member

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    My question may be somewhat stupid but I'm trying to teach myself photoshop, and I am trying to expand into the digital printing area. I am currently going to sub-out my printing needs until I can build a rep for digital printing...

    Ok, may 1st question is: When creating a fresh design what should my settings be (ex. New Document)? Does the ppi and color mode matter that much at this stage of design? And if so, what recommendations or calculations do you "normally" use for this?

    2nd, Some of the filters that I have used look really good (ex. EyeCandy 4000), but some filters don't appeal pleasing to the eye in areas of quality. They look "fairly" good on the screen, but look like they might not turn out so well when printed? What are some thoughts on screen looks versus actual printing looks?

    One more question and I will be done...sorry about all the newbie questions, but it seems like the place to ask!

    3rd, What can a printer's RIP do with the image in reference to changing resolution? Anything that would concern or matter to the designer? And How would some of you that do digital printing prefer to have files sent to you, as in resolution, file size, sized to scale or not?

    Not having the printer to play and test with, I just have some concerns as to tell a customer that I can make it look this certain way to have it come back totally crappy because of my ignorance...And as many probably know there's not that many books on "How to use photoshop for signmaking". :wink:

    Jay J

    And Bobby, Do you teach any photoshop lessons over at JSI Systems? Just thought I might ask! :smile:
     
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  2. Bobby H

    Bobby H Very Active Member

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    1st question (regarding ppi and color mode):
    Printers and service bureaus prefer everything in CMYK. You should only send them an RGB file if you have something screwy going on in your color management. I've seen Photoshop's gamma loader fight with Kodak CMS and then yield "double color managed" CMYK TIFF files that looked far worse than no color management at all. This situation has been nullified in Adobe's Creative Suite and further improved in CS2 (there's a single color management system for all apps --and now even a file management system that resembles feature's of Apple's "Tiger" OS).

    Pixels per inch is somewhat the same as dots per inch. In fact, 99% of the time, what people refer to these days as "dpi" is really "ppi."

    Pixels per inch is also something that only applies to print based output. I laugh most of the time I hear someone trying to apply dpi ratings to computer monitors. It doesn't work. A 1600 x 1200 desktop is only just that. It doesn't have a given dpi rating since that would be different from a 17", 19", 21" or 22" monitor showing that setting.

    Anyway, to get back to the answer of the question, your ppi level is going to vary from what kind of large format print job you're doing. Large billboards can be made with resolutions as low 8ppi --but that's applied to something like a 72' X 20' billboard face. Most billboards will range from 18ppi to 72ppi.

    Anything that can be viewed somewhat close should have ppi levels of at least 72ppi or more. 150ppi to 300ppi is usually enough. Poster sizes with resolutions higher than that are going to have really huge, unweildy files.

    Another handy tip: Try to keep anything in vector form in vector form. Graphics items like type, logos and other vector-based objects are going to print much sharper and more readable than they would when rasterized into bitmap form. This is one area where sending EPS and AI type files can be a better approach.

    Overall, you have to balance viewing distance and file size between each other when designing for large format output.

    2nd question:
    Answer: try to stay away from using obvious looking filter effects. They'll often make artwork have an amateur-ish look. Check out awards annuals for Print magazine and read other art and design magazines. Try to pick up on conventions that really work. You don't typically see award winning designs rife with Photoshop lens flares, Eye Candy bevel effects and Kai fractal textures.

    Filters can be handy, but be sure you use them in subtle ways to achieve a more original looking overall design.

    3rd question:
    RIPs have some ability to interpolate data, but not a whole lot. I've taken some 10' X 40' billboard designs and designed them at 18ppi and had them output at 72ppi with reasonbly decent results. However, these are images that are viewed from highways, not close up. For anything getting close scrutiny, I would not recommend having a RIP blow up an image anymore than 200% from its native resolution.

    Sorry if the post seemed long winded. Hopefully what I've written will seem clear.
     
  3. Fred Weiss

    Fred Weiss Merchant Member

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    Yes and yes. Working at too low a ppi is the most common mistake we see in the files we get. It makes everything move along faster in PS but makes for low quality output. I normally set my canvas at 100 ppi for the largest size I plan to print.

    Understanding color modes and the effect of color profiles takes time. RGB is preferable to work in for most image editing because some effects only work in RGB and because RGB has a wider gamut or range of colors possible. Most printers, however, will want a CMYK file from you. So with most files I create, I work in RGB and save in PSD format to preserve the layers. Then when I have a final master, I first flatten the layers, next convert to CMYK, set my profile ... usually Photoshop 5 CMYK, and inspect the results for any color shifts. Finally, save in TIF format for the printer.

    It's important to not change color modes while still in a multi layered mode and a warning dialog will caution you if you attempt to do so.

    If you don't already have one, get yourself a photo quality desktop inkjet and some glossy paper with which to proof your special effects. To look at actual sizes, select the layer you want to proof and copy it into a new window to help with size issues. If necessary, crop it so you can print it at full size on one page.

    I recently purchased an Epson R320 and a bulk ink system for it. This cuts my ink cost down to less than 2¢ a page to print full color. I also found a two sided gloss presentation paper at Office Depot which is priced at less than $15 for 150 sheets.

    I've all but stopped using Eye Candy. Take the time to play with the various layer effects and the Styles Palette instead. Use the Style Palette to generate effects and then go into Layer Styles and look at how it was achieved. The benefit here is that Layer Styles preserves all the editability of any effect and can be copied and pasted to a different layer. If it's text, you also retain your text editing. Once you accept an Eye Candy effect, you own it and retracing your steps later will be difficult to impossible.

    With any effect, be it with Eye Candy of PS Layer Styles, remember that you are working a larger pixel dimensions. Often the default settings will have very little visible effect. You have to go in and change some settings before you will see the effect.

    The printer's RIP is the bridge between your design at the pixel dimension at which it is saved and the printer at whatever DPI it is set to print your image. This is where silk purses are made from sow's ears. Which is great, but no excuse for not creating your image at a reasonable enough size that the RIP has lots of data in the color table upon which to draw. Printer's I farm out to often express pleasure at how my images print ... my only trick is what I've just related.

    When I am receiving images from others to be printed on my Edge, my usual response is to ask for the file in the native format of the application in which it was created. But that's just me and the fact that I understand more about getting an image from one point to another better than most "designers". Most printers today want either a TIF or a PDF that is final and in CMYK mode.



    I normally caution clients to expect some variation in color. We're not printing on paper after all. If a client responds in some way to indicate that they are looking for color matching or any other aspect which may be a problem to deliver, I either up my price substantially to allow for lots of test prints or I pass on the job. Most clients, in the final analysis, will back down in geometric proportion to an increase in price and will accept your promise of "best efforts".

    There are lots of resources that deal with digital printing on stocks other than paper including printing on films to be used in sign making. That has little to do with Photoshop. Photoshop is an image creation and editing application. You may want to check out Digital Graphics Magazine as a keystone in learning what you want to know. Between the magazine itself and the links and ads contained in it, you can learn a lot.

    Hope this helps.


     
  4. signguy95

    signguy95 Active Member

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    Thanks for the help...It really helps to have someone help out on certain things that are new to our business...

    So you think that 100ppi canvas should make my vehicle signs print at a pretty good resolution, right?

    And what resolution for vehicle signs should I request from anyone that's printing my designs?

    Thanks again to both of you for your help...anything else you might think I should know would be much appreciated! :thumb:
     
  5. Fred Weiss

    Fred Weiss Merchant Member

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    You're misusing the term resolution in your first question. Image or print quality would be more to the point.

    I can't give you a good answer as to what resolution to request. That's a question that should be asked of your printer and will vary with type of output and intended viewing distance. I would think that 300 x 300 would be fine for most situations. 720 x 720 would be a typical step up but not likely needed in most situations.Typical Scotchprint wraps are done at about 100 to 110 dpi. They're a little coarse up close, but at normal viewing distance they look great.
     
  6. Baz

    Baz Very Active Member

    If you want to desing something from scratch for you car you should first know what the final size (dimension) of you print will be. Once you know the size you create a new photoshop file at that size .. then set it anywhere from 75 to 100dpi will look sharp. If you want your file anyother size you have to make sure that it will end up at 75 to 100 dpi in the final output. I used to work at a quarter scale at 300dpi. Like mentioned before, large billboards will look acceptable at lower resolutions. Experience taught me to work at 100% because of repeated prints done over time (like fixing a damaged print).

    If you have vector shapes (ie:solid color lettering or logos) they would be better left as vectors applied overtop your bitmap image (picture). For images i prefer working in RGB. I get a closer match with what i see on my monitor and final output than printing CMYK (especially on fleshtones). I prefer CMYK for vectors since i find it much easyer to tweak the color by +/- the CMYK values.

    Your rip software wont make your images magically look sharp. What it will do is let you set the final size. Let you set the proper media profiles, controling ink amounts for different medias. Set output resolutions. Rendering intents for bitmaps and vectors. And other output settings and features. If you are not the one with the printer you dont have to worry about that. Just make sure your file is at a proper size and resolution.

    To verify a customers picture that has been given to you for reproduction you have to check the size and resolution of the file. For example, if its size is 3"x4" at 72dpi. Then it will look fantastic printed at a size of 3"x4". No more. If the 3"x4" file is at 300dpi then it will look good printed 4 times up. 12"x16".

    There are many other things that you can control in Photoshop to make your pictures come out the best they can but for starters you should concentrate on that. I strongly recomend getting a book on it to learn how to properly adjust picture levels and settings.

    Plugins like Eye candy are pretty good. Do not overuse. Its like overusing distortion effects in vector programs. Just because they are there doesnt mean its good to use them on everything. I personaly only use 2 Eye candy effects ( Chrome and wood) the rest i find look verry weak and unprofessional.

    Anyways im explaining this in laymens terms. I didnt go to digital printing university so i hope i helped in any way.
     
  7. Bobby H

    Bobby H Very Active Member

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    Be very careful about working between RGB and CMYK modes. You don't want a mix of CMYK vectors and RGB raster art in a file. The actual output file, be it a TIFF, EPS or whatever, needs to be all CMYK.

    Normally when I send a CD off to a large format service bureau, I'll include the file I want printed in the root directory of the disc along with a "read me" file explaining what all I did. Then I'll have a subfolder called "resources" that has other work files (layered RGB Photoshop files and other stuff). Sometimes there's the need for burning more than one disc if the files are getting really huge.
     
  8. Baz

    Baz Very Active Member


    Please explain why? I, more often than not, do my artwork in Illustrator. Vector type and logos usually are in CMYK and any picture i want to incorporate is in RGB. I hate Illustrator CS for not allowing me to do so anymore. Regardless i use version 8 for this purpose.
     
  9. Bobby H

    Bobby H Very Active Member

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    All artwork intended for print should be set in CMYK. Illustrator CS is trying to do you a favor in "pre-flighting" common user errors out of your document.

    It's best to end up with a final file in CMYK mainly for the purposes of having a more accurate idea of how your colors are going to print. RGB has a much wider gamut range than any printer can handle. Depending on the printer and RIP, you may wind up with errors in the print job.

    Finally, if you're going to use the same artwork to get things like four color process printing done, many imagesetter devices will reject artwork that is a hodge-podge of RGB and CMYK work. The problem will end up costing your client more money. The mix of RGB and CMYK in a single file is just as bad as all those CorelDRAW users who insist on coloring in objects with a ton of Pantone spot color fills (each spot color requires a separate printing plate).

    You can place RGB images in Illustrator and then easily convert them to CMYK. Go to Filter>Colors>Convert to CMYK.
     
  10. Baz

    Baz Very Active Member

    Yeah that analogy applies when you are looking for offset printing and color separations need to be done. But for Large format Inkjet printers, RGB and CMYK objects mixed in the same file doesnt seem to cause any trouble.

    At least not with my setup.
     
  11. signguy95

    signguy95 Active Member

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    Here's the file I am wanting printed...straight copy from a book I have been reading. So what do you think about this being printed. I have it in PS format if someone has the time to take a look at it for me, but heres the .jpg of the print!


    And thanks Baz for the help, laymens terms is what I understand the most!:Big Laugh
     

    Attached Files:

  12. Baz

    Baz Very Active Member

    You set your original size to 8"x10" at 100ppi. Thats the size it will look good at. It will look good increased by about 20% but bigger than that you will get a pixelated image (squares).
     
  13. signguy95

    signguy95 Active Member

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    but even if I recreate the logo at say something like 14" x 28" and I still use the 100ppi when creating it, it should still look very presentable, right? Or would you recommend using something like 300ppi?
     
  14. Baz

    Baz Very Active Member

    If you recreate the logo (not just resample what you have now ... that wont work) at 14"x28" at 100ppi it will look good at that size. If you create your 14"x28" logo at 300ppi. it will look good at that size and up to 56"x112" (your 300ppi file is increased by 400% and final output at that size ends up at 75ppi).

    Your 14"x28" 300ppi file wil be the same size(megabytes) than a 56"x112"75ppi file.
     
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