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Primer on resolution?

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keun

Technical User
Jul 15, 2005
262
US
Is there anywhere that you can point me to get a primer on resolution? I have ink drawings that are about 9" x 3" and I scan them at 1200 dpi. Then I create a Photoshop image that is about 12x12 and 1200 dpi and I drop the drawings on there, then transform them down to about 30% - 40%. So I put about 20 of my transformed drawings onto the Photoshop image.

I am printing on an Epson R2400, and I do not want to waste memory and space (and time!) with huge resolutions if I do not need them.

So, how do I find out which resolution I should use for my images, and how do I down sample the 1200 DPI JPEGs that I am putting combining in Photoshop?
 
...if your scans are true lineart bitmap (1 bit) images then they won't be very big anyway, compared to a greyscale or rgb/cmyk image. If they are anything other than 1 bit lineart bitmaps, then you'd be best to convert them to 1 bit and print...

...and as always, printing time is dependent on whether you print using the full capabilities of the printer or not, the amount of time to spool the image is determined by the resolution of the image and it's physical size in combination with your computers speed...

...best view this site for further study:


Andrew
 
Scan the images at as high a resolution as possible. Reducing the size is easy whereas increasing it while keeping quality is almost impossible. Of course, it depends on what you are doing with the files after and also, if you still have the drawings to re-scan at a later date.

Keith
 
Pay attention at this point: if you are using a 1-bit image (pure B/W), you cannot resize that image with interpolation (bicubic usually) just because you have no "intermediate" values, by definition. Only a entire value, 1/2 for example, can give you a not too bad result. So my advice is to scan your image at the print size, at least 600 dpi, or 1200 if your scanner has that high optic resolution (no interpolation). Don't worry about your printer "resolution", it's not resolution, just the number of dots!
 
I would always have the line art at 1200 dpi at print size. If you're sending it for lithographic printing then make sure you tell the printers there are line drawings and they can increase the lpi on ouput to get crisper lines.

But have them at least 1200 dpi at print size.

So you could scan at twice the size needed and save as 600 dpi, or you could have them half the size needed for print and scan at 2400 dpi.

Either way, they have to be 1200 dpi on output to get any sort of quality.

 
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