Printing and DPI

Ok just checked a lot of my images and they all seem to be 72dpi ( in photoshop cs4) however i am about to get some images prfessionaly printed and they are telling me they need to be a minimum of 100 dpi how can i resolve this?am i correct in thinking that the printer and software upscale the 72ppi image up to what it nativley prints at?however i know i can up the dpi in photoshop and obviously do this whilst not enlargeing the image

You will need to alter the images in the Image Menu of CS4.
Hopefully your file size will be large and you will have plenty of pixels, to create a more dense image.
Go into Image, Image Size.
See that the boxes for Scale Sizes, Constrain Propotions and Resample Image are all checked.ie switched on.
Change the Resolution from 72 to whatevever you need {I usually set a minimum figure of 180). However, if you file size is small, this will give you a small print size. If you file is too small, then uncheck the Resample image box. Photoshop will then upsize the pixel count.

ha ha just updated my post as wanted to make it clearer what i meant, and we have both posted at the same time thanks anyway

Hi, Foxy,

The resolution of your images is determined by the sensor, so many pixels wide by so many pixels deep. DPI comes into play only when you're spreading (or spreadin', as Pauly would say) those pixels over a piece of paper. The images from my Samsung GX10 come in at 310dpi for an A4 print.

Clearly, your Adobe programme is reporting the screen resolution for the picture, which could be 72dpi, 96dpi or some other number related to your monitor size, screen resolution, operating system or something equally irrelevant. Check the "image size" box or whatever Adobe calls it and stick in the printed size you want and the required dpi. Adjust this to 300dpi for photo-quality prints on your own printer and for printshop use.

I've long since abandoned Adobe for Serif PhhotoPlus, which I find can produce work to professional standards and costs a fraction of the price. It also has a superb forum. If you ask your question at http://forums.serif.com/forumdisplay.php?f=10 you'll no doubt receive a more-than-comprehensive answer. Tell them Al sent you.

Hope this helps (as they say)

Al Rogers




http://forums.serif.com/forumdisplay.php?f=10

It can seem confusing, but images in Photoshop are sized in ppi (pixels per inch). For web 72ppi is fine. For a top quality print or magazine reproduction 300ppi is the optimum. If necessary, resample the image using Bicubic (the default) or if you have CS2 or later then bicubic smoother (to increase size) and bicubic sharper (if reducing size for a web image).

The printer then reproduces those pixels with dots of ink, so the printer prints in dpi, bascially the more the better. My Epsom 1290s defaults to 720dpi, so in a sinmple sense each pixel would be made up of around 2 dots on ink. Not good enough, so I change that in the printer driver to 2880dpi, the maximum possible.

If you are disappointed with Epsom prints then it is likely that you are printing at a low quality setting by default. Advanced settings in the printer driver will open up things and there you can also make Custom settings for your favourite papers.

I have custom settings that I have called Photo Printing (colour on glossy paper) Monochrome (Mono on glossy) Matt Heavyweight (Colour on matt) and so on.

I read somewhere that you should use 300ppi for a HP printer and 360ppi for an Epson. 72ppi is probably an old printing standard.

For web use i.e. browser I didn't think it mattered. I've got an add-on for Firefox called "Image Zoom" so I'm not sure where the original vanilla settings are. I seem to remember that there were two options 1). Show Images full size, which I think meant actual pixels or 2). Shrink to screen, so I don't think ppi are used.

It's unlikely that any browser will display a 200 x 200 pixel photograph and bigger than 200 x 200 irrespective of what the ppi set to.

shim

Monitors display at 72ppi or 96ppi - you couldn't print a 72ppi image without it being very obviously pixelated.

If you have a Photoshop image open, regardless of its resolution you will be looking at it at monitor resolution. When you print it though it will be seen in all its glory, or otherwise.

hello there i am a little confused now, lol. when i print my images, they look fine i obviously select the paper type and crank up to higherst quality setting on the printer setting(photo high quality), so does this auto increase the dpi in the image i guess it does as it takes a lot longer to print

There are quite often presets depending on the individual printer, so for example our RX640 has settings like "Best Photo" or "Document" which certainly helps to simplify things.

There will no doubt be an Advanced tab that you can explore - take a look through the options and see what could be tweaked to improve your prints.

I always save to a tiff file for printing on my Epson RX585 as it is a loss less format and up the dpi to 96 it gives great 10x 8 print but takes ages to print.

I don't think you can actually be doing that jackitec, although I'm sure you think you are. 96dpi from the printer is not enough for a quality print. 96ppi in the image would be even worse.

If I shoot in raw, the image resolution is 240ppi, is this sufficient to get the good prints on a Hp printer, even if your save the image as a JPeg, the resolution stays at 240. I'm not sure where this fits in with DPI.

GlynM has just posted a link to a scanning site which confirms what I said above and that 72ppi came originally from the old 1984 Apple text screen and is now very much obsolete link The companies that put 72ppi in the file would be better putting 300ppi in at least that is used by HP and possibly Canon printers.

shim

You may well have the image saved at 96ppi, but when you print it, and you tell the printer driver that you want a 10x8 print, it will just increase the ppi until the image size is reduced to the size you want.

In case that doesn't make any sense, let's use an example!

Your photo is 3600 x 2400 pixels, and you've saved it at 96ppi. If you printed it at 96ppi, it would be 37.5 inches long (3600/96). If you tell the printer you want it to be 10 inches long, the printer divides 3600 by 10, to get 360ppi (pixels per inch). You now fit all 3600 of your pixels in a line 10 inches long.

A 10x8 print, of an image at 96ppi, would have the pixel dimensions of 960 x 768, which obviously wouldn't be making the most of your K20D.

This is an often used generalisation - my HP LP2275w, with a pixel pitch of 0.282mm, displays at 90ppi. One with a pitch of 0.294mm would be 86.4ppi. Others may be around 100ppi. It would be handy to be able to set your monitor's ppi in Photoshop to get exactly the right size shown if you view at 'print size'.

Dan

Read the link above Dan i.e. forget about monitor ppi

shim