Photo 'Resolution'

[charlie12345]

I want to include photos from a digital camera in a brochure. They need to be high-quality, to be printed via offset press, on gloss paper. I have yet to buy the camera for this effort; what 'resolution' (for lack of a better word) should the camera be/photos be shot at? TIFF format, I assume, so there is no loss of image quality. Size/space is not a problem. I posted this on the MS Publisher forum, but realised this forum might know more about image quality...

 

[maharg]

Hi Charlie,

Comments below based purely on my experience .

Depends how big the printed pictures are going to be, and what resolution your printer will produces the screens at.

Size x quality = cost x cost !

As a rough guess, let's say you'll be printing A4 brochures.

A 2Mega pixel camera pushed to its top limits will allow a 1400 x 1400 dot resolution. If you are printing 600 dpi (dots per inch) that gives you 2.3" x 2.3" roughly. Any bigger and you may start to see the pixelation. Try and keep well below the limit, or use a camera with higher resolution.

Your printer will want you to save your photos in CMYK format rather than RGB. Check whether he/she uses a Mac system (likely) or PC, because there are compatibility issues here which can be tricky to resolve.

A method I've used very successfully for any platform, Mac or PC, is to save my work as a high resolution .pdf file in CMYK . All the printers I've worked with have come up with good results for me without any compatibility headaches.

Hope this helps, and good luck!

 

[charlie12345]

So the answer is, I need to know the screen resolution the printer will use, and compare that to the maximum size of the photos as they will be published... ?

 

[charlie12345]

sorry - i just repeated what you said......... duh.
The next question is, if the photo is used 'full-size', or 1:1, does the pixel resolution get better if the photo is made smaller - ie, if the 1400x1400 image is 1:1 at 2.3", will it be 2800x2800 at 1.5" (or something smaller like that). ?

 

[maharg]

Charlie,

No, at best, the resolution will stay the same, but the distance between pixels could be smaller if you make the picture smaller.

Think of resolution as the amount of information the picture contains - a good example is a roman mosaic picture, made up of lots of small tiles. When you take your digital pic, if your camera has 2 million pixels, you've got 2 million tiles to use for your picture. (Hence the 1400 x 1400 approximation I mentioned earlier, which assumes a square format).

If you make your picture smaller, you either need to use smaller tiles (increase the dpi.) or use fewer tiles. There's no point using resolution which is beyond the eye's limit of resolution, you just need to use enough to make a 'good enough for your needs' picture.

Your printer will be the best guy to ask about what resolution you need and he should be able to show you samples of work at various resolutions. I find 600 dpi pretty good, but I don't know what your expectations are .

So you'll reduce picture resolution if you reduce the size of the picture but keep the dpi value the same .

Hope that helps, good luck.

Regards,

Graham

 

[blueark]

If it's a photo, 600dpi is probably way too high! The resolution you should use is actually twice the screen ruling (usually measured in lines per inch or lpi). Don't confuse this with dpi! A printer might be using a 2,400 dpi imagesetter, but the screen ruling is likely to be only around 150lpi. You won't see any improvement in your photo over 300dpi.

Say you have an image 1400x1400 pixels, at 300dpi you should get 4.6x4.6" out of your picture. If you print it at twice that size, the resolution effectively drops to 150dpi. It's still 1400x1400, but spread over a larger area, so the individual pixels are twice as big, and therefore more noticable.

If, on the other hand, you print it at half size, the resolution doubles to 600dpi, but as I pointed out, you will actually lose detail because the printer won't be able to make use of every pixel. You're better off reducing your image to 700x700 to save a bit of memory and to be nice to your printer!