Best image formats for .pdf?

[Jack Aidley]

Hi there,

The images for Great Ork Gods are (finally) getting done - but I'm unsure about what image formats I should be getting my brother to give them to me in.

I've seen people asking for images in .gif or .png format - are these good choices? What is the difference between them?

I've seen people asking for between 300dpi and 600dpi - will the difference noticable at 'home printing' quality? I assume either is fine for screen use?

Are there any measures I can take to keep the image size down?

Cheers,

Jack Aidley.

[Matt Wilson]

Jack:

What are you using to do your layout?

I would recommend asking for the images as TIFs at as high a resolution as you can get, just in case you ever want to do a print version. Minimum 300 dpi. 600 if you can get it.

If you plan on selling the game as a downloadable pdf, you can choose to export to various image resolutions when the time comes. For home printing, 150 dpi is probably plenty.

[Eero Tuovinen]

GIF is only suitable for drawings and such, which have only a limited amount of color and detail (it's a palette-based format). Essentially useless for other than html-based publishing.

JPG is suitable for photos and other complex pictures, especially for web purposes, as it is a loss-compressed format. That means that they can be really small, but the compactness is achieved by algorithmically reducing the level of detail in the picture. A big no-no in print publishing, but acceptable in the web if you know what you're doing.

PNG is a good, modern format that replaces GIF for most purposes. It compresses somewhat better and has more image options (alpha channels, gamma correction and stuff, not really important for you). It should be used instead of GIF and JPG when possible, although the latter is still better if you want the pictures to be really small.

TIFF (Tagged Image File Format) is a customizable format for professional picture work. Most graphical programs have their own implementations, which means that the formats are not always interchangeable even when they are TIFs. Easily the most heavyduty of these, and recommended if you have the programs to use it.

For actual print work you'll want uncompressed PNG/JPG, or better yet, TIFF, which has been the format of choice in the print industry for years. As Matt said, the more resolution the better. You can always downgrade, but going to the other direction is impossible.

So, in summary: take TIFF and convert it yourself to PNG or JPG to use it in a PDF publication. 150dpi is enough for home printing, but the "master copies" should be 600dpi or even 1200 for line art. The goal is to keep your options open for later on, while not burdening your PDF customers with gigantic TIFs.

[Matt Snyder]

It depends on the artwork.

If your artwork is line art (that is, ALL black, not grayscale, no shades of gray or color for that matter) the best way to go is .EPS format. This stands for Encapsulated PostScript. PDF handles these things wonderfully, because they're so economical on file size. They can look funky on screen, but they look fantastic printed out. Usually ok on screen, too. I use the format often in my own PDFs.

That said, TIFF is usually the way to go, for grayscale or color (CMYK or RGB format).

GIF has been covered. I'd strongly recommend not using it. It's a compression format, and not well suited to things like PDFs which you'll print out.

The issue for PDF is file size. Images will make your PDF file size sky-rocket. One way to help prevent this is to use slightly lower resolution for your images. Images are usually 300 dpi (dots per inch), which people usually call "hi res". I like to cut that in half for my PDFs. The trade off is a not-very-noticable image quality loss for a very-noticable file size economy. That is, the print outs are only slightly less quality (most folks won't notice) and the file size of the PDF is noticably smaller. Good trade!

[Jack Aidley]

Cool.

Thanks for your feedback. The art's a mixture of ink and pencil drawings - all greyscale but not strict black/white. I'm currently using Word to write the text, and then OpenOffice to convert to .pdfs - which isn't the best I know, so I'm trying to source some ex-training copies of the Adobe Illustrator and Acrobat on the cheap.

So, we're looking at TIFF as probably the best format. And 300dpi being plentry - but with less still being a valid option? Incidently, is there any reason dpi counts seem to go 150, 300, 600, 1200? Can one do, say, 200 dpi?

[Luke]

One can do 200 dpi.

Hi Jack,

In your source document, you should have all your images imported at 300 dpi minimum. It's just a good safety margin. When you output the pdf you can always tell the software to downsample, i.e. reduce the resolution.

Laser and Ink Jet printers output at 150 dpi. So you can safely downsample your pdfs to 150 dpi. (This doesn't apply for line art and illustrator .eps files. They don't need to be downsampled.)

To further reduce the size of your file, first save all your BW illustrations as TIFs with LZW compression turned on. This compression method is great for our purposes because it compresses solid colors. So that white background that the illos use doesn't eat up memory under LZW.

Next, output your PDF (at 150 DPI) with all the compression options turned on: JPG compression, ZIP compression, CITT Group 4 compression, compress line art and text. Play with the individual levels until you have a small file with clean text and no pixelation in the images.

Hope that helps,
-Luke

[madelf]

As an artist, I've never worked for a publisher (even a print publisher) who was concerned with getting images over 300dpi, even for ink drawings (in fact, many digital artists start their original work at 300 dpi), so I would suspect demanding 600 to 1200dpi is probably overkill. It might be standard practice for high-end mainstream publishing, but it sure doesn't look like most of the rpg industry is using it.

If you are concerned with the quality of line art at 300dpi, it's easy enough to scan an inked black and white drawing as grayscale rather than line art (this is something that has been reqested of me before, though rarely).

[Paul Czege]

As an artist, I've never worked for a publisher (even a print publisher) who was concerned with getting images over 300dpi, even for ink drawings (in fact, many digital artists start their original work at 300 dpi), so I would suspect demanding 600 to 1200dpi is probably overkill. It might be standard practice for high-end mainstream publishing, but it sure doesn't look like most of the rpg industry is using it.

I told Colin I wanted 300 dpi for the interior illustrations he did for My Life with Master, figuring that would be sufficient. Only after he started working did I learn that the press would do 600 dpi. Had I known earlier, I would have had him working at 600dpi. Similarly, I had Will deliver a 600 dpi scan of the artwork he did for the cover, again figuring that would be sufficient. The output resolution for the press that printed it was twice that: 1200 dpi.

Paul

[Ron Edwards]

Hello,

Regarding resolution, you can always reduce it, but you can't increase it from your starting point.

With that in mind, I always request 600 dpi. I can't think of any reason for requesting the scan to be any less resolved.

Best,
Ron

[Luke]

As an artist, I've never worked for a publisher (even a print publisher) who was concerned with getting images over 300dpi, even for ink drawings (in fact, many digital artists start their original work at 300 dpi), so I would suspect demanding 600 to 1200dpi is probably overkill. It might be standard practice for high-end mainstream publishing, but it sure doesn't look like most of the rpg industry is using it.

As I said above, for laser printers, 150 dpi is fine. For professional work: First, you always want to have your images higher resolution than you need them. Preferrably at least twice as large. That way, if you modify the layout and need to use the image bigger you don't have to worry about it pixelating.

Second, printing presses (rip to film to plate) can print up to 2400 dpi. That's the reason that text is so smooth and clean. So if you want your line art (straight black and white) art to print as cleanly as text, 600 dpi and 1200 dpi are reasonable and recommended. Grayscale stuff is different, because it uses different dots to reproduce -- half tone dots. So 300-600 dpi is about the best quality for reproduction there.

The proof is in the pudding, though. Look at the illustrations in MLwM and Burning Wheel. Clean.

-L

[madelf]

Hey, I'm just working from what I've experienced & what I can actually produce. On that basis...

I could work with you on the 600dpi interior illustrations. I'd have to know in advance, but it's doable without any problem.

For cover work...
I generally do my paintings digitally. I've got a 2.26GHz. pentium 4, with 512MB of ram and Painter7 as my software of choice - not cutting edge anymore, but no slowpoke either. I'd generally use 600dpi for a cover (to be printed) as the default, just because it's more critical than the interior filler art.

A 1200dpi cover, I could probably provide. But I'd have to charge you somewhat of a premium price because it's going to be slow going.
I wouldn't even try to do a 2400dpi painting digitally. (In fact I just checked Painter7 and I actually can't ... it won't even allow me to set the document to 2400dpi)  So I'd have to turn down the job if you wanted a cover at that resolution, unless you wanted to about triple my normal rate to do it in traditional medium and have it professionally photographed. That's the only way it could be done.

And really... I personally doubt that your eye would notice the difference from 300 to 600 or 1200 to 2400 (or even 600 to 2400, honestly) unless you had both versions side by side and inspected them closer than anyone reading a book is ever likely to.

But if you want quality that high... and you're willing to pay what it takes... I don't doubt that you'll have a fine product.

I just think it would be serious overkill for the kind of products rpg publishers are producing. Considering that a few years ago West End Games was asking for 300dpi line art for their Metabarons line (some of the nicest looking rpg books I've ever seen), I have to assume that thinking someone needs 600 or 1200 dpi line art for an indy rpg is a bit much. (and as I suggested before, just scan the ink drawings as grayscale if you're worried about it)

[Malak]

Right, there are two things to know here; Line art & contunuious tone.Right, there are two things to know here; Line art & continuous tone.

Line art is where there are black lines that come to a razor-sharp stop, with no blurring edges, i.e. the traditional pen and ink drawings.

These require very high rez art to reproduce crisply. Professional print quality is 1200dpi. However, you want a bitmap format (not as in the file type, but is in the mode in photoshop) where the only two colours in the file are black & white. The file sizes for these babies can be really small, esp. if you save the file as a tiff with zip compression (which your PDF creator should be able to do for you).

600dpi should be fine for print quality normally though, but I'd have my master file as 1200dpi anyway.

Now Continuous Tone is where (in either B+W or colour) is where you get graduations in tone & colour. 300-600dpi is fine for this.

[dredd_funk]

There's been a lot of good advice but I thought I'd just emphasize a couple of things that others have already said that might get buried all-to-easily.

Background-wise, I'm neither printer nor artist, but I spent several years in a previous job managing all the publications for a small business (flyers, books, conference materials, promotional materials, etc.), which meant taking graphics from design to the page, to the web, to PDFs, over and over.  Given the small size of our organization, it was really a lot like indie-publishing a work, only doing it over and over and over.

First DPI isn't the only factor to be aware of in scaling images.  It seems redundant, but the original 'print' size of the image is just as big of a factor.  An image done at 2400dpi but whose original size was 1x1", will look worse when printed at 12x12" than an image done at 600dpi but whose original size was 6x6".  The 1x1" image is being scaled to 12x its normal size, which reduces its dpi to 1/12 of the orignal (it's a simple inverse relationship) and 1/12 of 2400 is 200.  However, the 6x6" image is only being scaled to 2x its normal size, reducing its dpi to 1/2 the original and 1/2 of 600 is 300.  Take home information: both the original 'print' size and the dpi set the scaleability of your image.  Digital Images are, mostly, mosaics and both the density of the dots and the size of the original canvas matter when scaling. [If what you want can be done 100% with vector-based art, you have no problem scaling at all.]

For 99.9% of the art--at a guess--that most folks will want in their books, you won't care much, because you won't be scaling them to, say, banner size.  If you have a particular graphic that you want to become your game's 'signature' graphic, however, I would strongly suggest getting it done in a size/dpi that can be scaled upward for use in large promotional materials.  Prior to starting at my old job, the company had a new logo done.  It was 600dpi, but it was only 2x2".  It turned out great for business cards, stationary and folders, trying to get it to look good on a huge banner for our annual conference was a nightmare!

Note: this probably won't help your artist if he/she tells you that they can't do something at 1200dpi because it would be too slow on their computer.  What slows down the hardware is the pixel count--and the grind of manipulating it--in the image.  In the example above, the 1x1" 2400dpi image has a pixel count of 2400, while the 6x6" 600dpi image has a pixel count of 3600.  The second image will be larger and will consume more resources than the first.

Second, madelf is precisely right in asserting that you'd probably never notice the difference between 300, 600, 1200 and 2400 dpi, visually.  Anything above 300 dpi will look good in print at the size it was intended.  The only problem with a 300dpi work is what happens when you need to scale it larger than was originally intended, as mentioned above.  If you think this will never happen, I'm happy for you!!  In nine years of doing this type of stuff I learned one valuable lesson: never, ever, ever, ever, ever, say never...

Finally, about the only time you want to, in fact, scale an image up, is for actual 'print' materials.  Anytime you go to PDFs, the web, any computer-based distribution of materials you are almost invariably scaling down.  So, make sure you've got your images in a size/format that suits your printing needs first, and carefully consider what those needs might be not just for now, but in the future.  Images suitable for large scale print materials can almost always be reformatted to suit your electronic needs.

Note that this isn't always the case--scaling far enough 'down' can eventually cause the image 'look' to degrade.  Why?  Because you're tossing out information (pixels) when you scale down, and at some point a valuable piece of information is going to get tossed.  All of a sudden a particular line won't be clear and it changes the look of the entire graphic.  This can happen.  You don't want to take something that was carefully crafted to look good at 24x24" and try to scale it down to 0.25x0.25".  Aside from vector-based graphics, you won't ever achieve 'perfect' scalability.  The best you can do is ensure you get a graphic that falls in your particular 'sweet spot' range in terms of print/display size.  So I wouldn't suggest going to an artist and saying, "hey, create me a logo that is 48x48" at 600dpi," because you expect your game to have its own conference.  If you do that, your logo may not look quite right for your book (it probably will but you need to be careful).

I hope all of this wasn't preachy sounding, I sure didn't mean for it to be.  If someone thinks I've got something wrong, I'm happy to be corrected by the more knowledgeable.

Cheers
Chris

[Malak]

Second, madelf is precisely right in asserting that you'd probably never notice the difference between 300, 600, 1200 and 2400 dpi, visually.  Anything above 300 dpi will look good in print at the size it was intended.

All excellent points Chris, however although you're right on continuious tone images, at 300dpi you will spot jaggies on B+W line art (in print at least).

However for on-screen use I'd print even line-art as a grayscale image, probably at just 150dpi. That's not to say that my original art on file won't be a 1200dpi bohemouth for my dream printed project!

[dredd_funk]

malak - you're absolutely right!  Somewhere I mentioned that line art was different but--lol--it got 'buried', which was what I was trying not to do.

Cheers
Chris