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The other constraint is that people who sew are often not computer experts, so whatever solution I settle on has to be very, very simple for the user. And has to work reliably on every model of printer, all around the world.
Here's where I need your help:
As far as I can tell, GIF files don't always print at their true size. See my test pattern at [quiltersreview.com...]
When I open the GIF in PaintShop Pro, it tells me it's a perfect 6" by 6". Whether you print the page or click on the link and print just the GIF, you may or may not get a 6" x 6" test pattern. On my printer, I get 4.75" x 4.75".
So my question for you is:
Can I create simple GIF graphics and expect them to print at exactly the same size on everybody's printer, without expecting the user to do anything fancy?
Can anybody tell me the relationship between the size of a GIF reported in PaintShop Pro and the size at which the image prints? (See first post, above, for details.)
I would make a gif version that people could see on the web but save the actual file to a tiff, pict, bmp, targa, or something more printable. You could even really save it as a jpg just higher compression. Just link from the gif preview to the larger file. This should initiate a download to open in the users own editor. You could even have links to free editors off your site.
Don't trust a browsers to render or print graphics.
Then you have the big headache about paper size. While Americans are using paper sizes called "Legal" and "Executive", Europeans are using "A5" and "A4" -- and the height/width ratios are very different (A4 is noticeably narrower and longer than the nearest American equivalent -- if I have to photocopy a letter from America, I have to copy it at about 90% so that it will fit).
Different browsers, printers and operating systems will give different results.
Re: sewing patterns...these are actually quilting templates, so the pieces are all small (2" to 6") and normal printer paper is fine. Trust me on that.
Re: the printer changing the resolution. This sounds like an important clue!
Does everyone agree that when a typical PC user prints a typical GIF from the typical browser on their typical printer, the GIF will typically be printed at a higher resolution than 72 and therefore appear smaller than it was designed to?
That would certainly explain a lot.
(No offense, Korkus2000 -- I always take a poll on any "keystone" fact like this. I really appreciate your bringing it up!)
AFAIK, it depends entirely on the printer and it's driver software. Some printers have "features" that are designed to smooth web graphics when printed, which would affect any gif image...
I would also recommend using PDF format, with the grpahics designed at a minimum 150ppi resolution. 300ppi would be better for detailed images, but I'd imagine quilting templates are mostly fairly simple outline images, so it shouldn't be a problem.
The problem is that graphics editors usually assume that you are working with dots, not pixels; for the web, you will normally be working with pixels rather than dots. Things start to go awry when the browser has to convert from ppi to dpi. How many ppi does the browser assume?
Half-toning (and therefore dpi) isn't something you'd need to deal with at all, until you send your image to a professional printing press. In which case, get specifications from your print shop... most of them will just specify a file type & minimum ppi resolution, and can handle the half-toning and color separations themselves.
If you're talking about folks printing your files on their home printers, ppi is the only resolution setting you need to deal with. In that case, any ppi setting high enough to prevent "jaggies" (visible pixellation) in the printed output is good enough. 150 is a good minimum for good inkjet output, in my experience.
But there's no option for such fanciness with GIF format... it's really intended just for on-screen display, and defaults to 72ppi.
Clear as mud? ;)
1) GIF defaults to 72ppi. (Side issue: Is it possible to have a GIF at other than 72ppi?)
2) Printers think in dpi, not ppi.
3) Therefore, the printer must translate the GIF from ppi to dpi.
4) The assumptions the printer makes about the number of dots per pixel (or pixels per dot) determines the final printed size of your GIF.
If the translation of ppi to dpi were handled numerically the same across most printers, then I'd be all set -- I'd just have to take that conversion into account when I create my GIF.
What do you think? Do most printers translate pixels to dots the same (numerically)?
I'm not sure about those points. Some printers actually advertise a feature for
"smoothing" web graphics... others don't. I've never had a problem with my Epson printers changing the dimensions of GIFs though.
I don't think, however, that there is anything as specific as an actual "dots per pixel" number. The printed "pixels" in a 300ppi 2x2 image would be much smaller than those in a 72ppi 2x2 graphic... as the 300ppi image would be 600pixels x 600pixels in that two inch space, while the 72ppi image would only be 144p x 144p... so the printer wouldn't really be able to have a simple "dots per pixel" conversion.
The printer probably doesn't "think" in dpi at all. In conventional printing (such as newspapers & magazines), DPI refers to the number of halftone dots per inch in a "screened" image. Inkjets don't use halftone dots, and I'm honestly not sure what their "dpi" rating means... it could be the number of halftone dots they can print per square inch before the dots get blurry and bleed together, but I really don't know.
I don't know of any way to create a GIF at higher than 72ppi. Check to see if your printer's settings have some kind of "smoothing" option you could turn off.
Also, double check the pixel dimensions of your GIFs... ignore the "inches" measurements your software is giving you. If you want a 4" x 4" printed image from a 72ppi GIF file, the file should be 288 x 288 pixels...
The problem is, Macs display at 72ppi and Windows displays at 96ppi. Also, most printer not will print truly accurate measurements, because they are too dependent on software drivers. About the only printers you can depend on are PostScript printers, because they all use similar drivers. Most people don't use PostScript printers, because they are more expensive.
I heartily recommend using PDF format because:
1) The format is compressed and downloads quickly.
2) You can use Page Layout Software to create the patterns, such as PageMaker, to assure you the most accurate measurements possible. With page layout software, you can resize the graphics to any size you desire.
3) Acrobat is a worldwide standard for compatibility in documents. Almost everybody uses it. The reader is freely downloadable from adobe.com.
4) It would be very easy for unexperienced users to use.
<non expert opinion>I say PDF all the way.</non expert opinion>
This should work, and since it's merely a pattern and not a work of art, you could probably get away with an image designed to print at even 3 inches and stretch it to 6 in the document and it'd still work because the contents of the page hasn't changed, just the available print area.
In answer to a previous question, yes, GIF files can be of something different than 72, but GIF's are mainly for onscreen viewing, not printing - they'd use TIF or TGA files for quality printing.
The key here is that you're looking for a small file size (GIF's are fine, JPG's might be better) but printing gets fishy when you try to print them raw because your printer will try to make best use of the page, by default. By saving it into a formatted document designed to be printed, you eliminate that headache.
[edited afterthought] Oh, and yes, they're right about PDF files, but you're looking at buying and learning new software. You should be just fine if you use word or some other word processor.
72 dpi = Web Graphics
200, 300, 600, 1200, etc. dpi = Print Graphics
Go into any graphic editor and change the dpi to 300.
Then change the dimensions of the graphic from pixels to inches.
Most graphics will be something like "40px X 45px".
Change this to the size of the swatch/pattern, "2in X 3in".
Remember, for a graphic to print - it really only needs to be the right dimensions measured in inches. For it to print in better quality, the graphic should not only be measured in inches, but it should then be a higher DPI (dots per inch - 300 is standard, 600 is high-quality for logos and such, 1200 and up is usually used for industrial print jobs).
Nice! I'm now a full member. :)
So if you want to make absolutely sure all of your users get the image to print at 3" x 3", giving them a raw gif image probably will not do the trick, given the vagaries of modern printer drivers and default scaling options that novice users may not be aware of.
The printer driver, though, is probably working at 300dpi. That means one pixel becomes 4.167x4.167 printer dots. But you can't have 0.167 of a dot, so the printer makes it 4. That's probably where the error comes from, and the reason why the image prints out smaller.
Change to 300dpi, and it should work -- if the user has his or her printer set to 300dpi.
A printer dot is the smallest dot a printer can print. For an inkjet printer, it's easy to visualize: the dot made by the smallest drop of ink the hardware and software will allow. 300dpi is fairly normal, and the dots are much smaller than the half-tone dots in newsprint -- but they're still dots.
Some browsers running on Windows had a problem when printing out text in sizes specified in pixels: they simply translated pixels into dots. Text specified as 12px printed out as 12 dots high -- at 300dpi, that's illegible. That now doesn't affect many people, but for a while px were, for that reason, not a recommended unit of measurement in CSS.
Incidentally, I can create GIFs of 300dpi and more with my graphics editor. At that resolution, an image 800x600 pixels (a screenshot, say), fills the entire screen, but prints out at 2.67x2 inches.
[edited by: rewboss at 5:43 pm (utc) on June 12, 2002]
OK. So it IS possible, but there isn't much reason to use GIF for high-res work... Thanks for straightening that out! If I'm working high res, I always just use TIFF.
I wasn't sure if inkjet printer DPI ratings were actually referring to the ink droplet size, because when I look at an inkjet print these days, the printer specs may say 1200dpi, but it sure looks like you could fit more than 1200 of the ink drops into an inch...
Do you happen to know if inkjets are measured by how many droplets per inch they can produce without them bleeding together? Or what specific measurement is used? I've never found DPI measurements to be any use for anything except halftone screens, just because no other application of the measurement seems very standardized.
What you are trying to do, as you can see, is a tough one on the web. Thats why the folks at adobe created PDF. It is used for exactly what you are trying to do. Really anything else is going to be a hack.
also paper quality and the actual ink/toner does matter. I have seen inkjets print at 1440 dpi. They have no comparisson to 600dpi from a fiery. There are a lot of variables when it comes to printing. Thats why I am a web designer. Its much easier than print. No gamut and stuff like that.
Does paintshop pro not have a print size view like photoshop?
Do you happen to know if inkjets are measured by how many droplets per inch they can produce without them bleeding together?
Along with every image in the PDF file, include an image of a ruler showing inches and centimeters. That way the user who prints it can compare the ruler image to a real ruler to verify that the printed pattern is the correct size -- AND (this is where I feel really clever), if the printed pattern is not, most photcopiers will enlage/reduce by percentages (e.g., 92%, 105%) which, with a little trial and error, could be used to make a photocopy exactly the right size. If the pattern is a black-and-white line image, a second-generation photocopy would probably be okay.