DPI

[LesC2009]

When I've edited a picture in Photoshop and then want to save it for printing, does it matter if I leave the DPI at the default of 72 or should I change it to 300? Or is the DPI in photoshop just an indication of how large you can print the picture at? Or does it depend on how big you want to print too?

And as to sharpening - They say you should always view at 100% for sharpening... so if you view your picture at 100%, you might say be able to raise sharpening to 100% which looks fine. However, if you then look at the sharpened picture in photoshop at 'actual print size' - about 12" x 8" it looks oversharpened. So will it look oversharpened too if printed at that size??

[EOS_User]

Re: DPI

This is a massive subject; there are volumes and volumes about this on the web and elsewhere; but, in short, here goes...

DPI is simply a measure - Dots Per Inch. 72 is the standard for a regular on-screen display; hence the Photoshop default, while 300 is the standard for best-quality printed work. There is no perceivable difference in printing at a density any higher than 300, but you can normally get away with safely printing at 250 DPI if you need a slightly larger print, and the further away you are from a print, the lower you can go with DPI, down to about 150 for a large poster viewed from say 6' away.

None of that changes the pixel dimensions of the image, so changing the DPI in Photoshop doesn't make any real difference - provided always that 're-sample image' is turned OFF! That said, any image I work on, I always change the DPI to 300 (you can set that as your default in DPP if you shoot RAW), so I easily know what the optimum printed image size might be. (It saves me having to do the maths later!)

So, if you want to know what your optimum print-size will be for any image simply take the pixel dimensions and divide by your chosen DPI rate (300 for best, 250 for everyday use etc). E.g. a 6000x4000 image will print at 20"x13" @ 300dpi but at 24"x16" @ 250dpi. etc. etc. etc.

Sharpening meanwhile is a whole different subject, and is very much a subjective issue. In general printed images require more sharpening than displayed images; so it's very difficult to judge initially that what you see on screen will translate into what you want to see printed. You really need to run a few tests to determine what works for you. My tendancy is to push the on-screen displayed image to the limit of 'acceptable sharpness', at which point I pretty well know that my printed image is going to look as I want it to be. Some people prefer sharper images; some softer. You will need to make your own judgement about what looks good to your eye - given that any print will be for you, rather than a.n.other...

Hope that helps.

Lee

[BobEH]

Re: DPI

Or you can decide on the size of your print; and in PS go to Image/ Image Size and in the drop down box input the first important dimension. The other dimension will automatically change as long as "Constrain Proportions" is ticked. You will notice that the figure in the resolution box will then change to the new DPI figure. As long as this remains above about 200 all should be well. If you have a Canon printer, you can use the PS plug in "Canon Easy Photo Print (Pro) " An excellent bit of software which sorts out your prints for you. Even if the new resolution is say 347 dpi.