Standard DPI for printing

[kevinbythebeach]

I was wondering what standard printing DPI is for 4x6 and A4? Thanks

[Davey]

For me I usually stick at 300ppi for images as that's what most my settings are defaulting at or what my sources are in, also it gives me standardised indication of the print size in relation to image resolution without having to work it out for different values (ie. print size at any given res is identical for all my images and things). Be aware DPI doesn't change the resolution just the size it's instructed to print at unless you resample the image that is, but obviously PPI is tied to resolution and many apps use this value due instead.

Saying that I think 2592 x 1944 pix image at 200dpi will print (on a a4 printer capable of 300dpi) pretty much identical to a 300dpi one unless you really really scrutinise it (it has to be on a suitable paper that is designed for that kind of fine printing too). Between 200 and 300 should be fine. Size of print and viewing distance as ever are the determining factors so a4 for your wall is not the same as a4 for an album.

Edit: Obviously you've thought of this but I've heard of people doing it so recommend not to but don't think changing the dpi alone will make the image more printable, it's simply value for print size not a magic number for making things print better as no doubt you know. If the info isn't there you can't print it ie. a 800x600 image at 72dpi being scaled up to 150dpi will make no difference other than telling the printer to double it up.

[Colin Southern]

I was wondering what standard printing DPI is for 4x6 and A4? Thanks

I can't speak for others, but personally I keep the pixel dimensions at whatever they were shot at - tell Photoshop what size I want the image - and the DPI is whatever it is.

If the DPI is higher than needed then I could down-sample the image, but there's little point as it doesn't make any difference to the quality (although it will make for a smaller file size if that's important).

If the DPI is lower than desireable then there's not a lot that can be done about it, and it usually doesn't make a lot of difference anyway as the bigger the print the greater the viewing distance, and the less our eyes can resolve small detail.

[Geoff F]

I assume that you are talking about computer pixels per square inch (ppi) and not printer settings of printing dots per inch (dpi) as the two mean totally different things. Average printers can print between around 300 and 2880 ink dots per inch.

As the previous replies suggest there isn't one simple answer to the best computer image resolution. I find that for standard printing there isn't a lot to be gained by sending a resolution above 300 ppi to a printer/home printing providing the image is at the correct required printed dimensions.

Some establishments require images for printing to be at 300 ppi but when doing my own printing I can get away with as low as 150 ppi on softer cheaper paper.

So ideally a 6 x 4 image at 300 ppi would be 1800 x 1200 pixels at 300 ppi.

The complicated bit comes with exactly how you resize the image if you have to do any considerable size alteration which means adding or losing a lot of pixels. But perhaps, that is another question.

[Colin Southern]

Some establishments require images for printing to be at 300 ppi

Between you and me, I think that this requirement is often more "mantra" than based on anything substantial. We've had instances where heavily cropped shots have come in at less than this for the likes of calendars - printer adament about the old "300 dpi" - so we just up-sampled in Photoshop and they couldn't tell the difference

I usually work around 180dpi as standard, but have gone much lower with perfectly acceptable results. The ONLY difference it make is to the viewing distance.