Comments on: Pixels per inch for web

By: René

René — Wed, 01 Feb 2012 11:23:06 +0000

You might want to read this blogpost: http://www.getcolormanaged.com/color-management/saveforweb/

By: Walter

Walter — Tue, 31 Jan 2012 21:36:48 +0000

I came to this page for the reason that photoshop requires input and because I am trying to figure out why it is that after I save the image/logo to a jpg the colours don’t appear the same as they do in the PS project? I thought perhaps this setting may have an affect, but now it seems it may not.

By: Peter

Peter — Tue, 06 Jul 2010 09:49:28 +0000

PPI is exactly what it means–”pixels per inch.” It specifies how many pixels of the image will print in a single inch in the print output. So a 1000 x 1000 pixel image printed at 100 PPI will have dimensions of 10″ x 10″. PPI might be better described as “pixels per PRINTED inch,” but as it is sometimes used to describe the pixel density of display devices (e.g. monitors, projectors, and mobile phones), the reference to printing is not always applicable. For such displays, PPI is generally a fixed property–i.e., the display has a certain fixed number of physical pixels per linear inch, and it can be found by measuring the display as described in the above post. But when Photoshop asks for PPI in the Image Size dialog, this value is used to determine how PS converts the pixel dimensions of the image into printed inches. As such it affects how other dialogs, tools, and info palettes will show measured dimensions (if they are set to display units in inches/cm). PS can also use this PPI value to print at the desired size, or you can adjust the print size in the Print dialog as well.

The choice of how many pixels per inch of printed output will correspond to a satisfactory result depends on the nature of the image, the intended viewing distance, the type of print media, and other subjective factors. It is premature to assume that a single “magic” value–or even range of values–is best under all circumstances. The optimal PPI must always be selected on a case-by-case basis. And this is why PS has such a feature in the Image Size dialog.

By: René

René — Tue, 06 Apr 2010 18:04:59 +0000

That’s how it works
For a “decent” print, you need about 150 – 200 ppi. For a “good” print, something like 200 – 300 ppi. Depends on the printed size as well: A large print (say 40x60cm) won’t be viewed from as close as a 10x15cm print.

By: Hybeagle

Hybeagle — Mon, 05 Apr 2010 19:28:49 +0000

After reading the article, I get it that the PPI is only used for printing the image. Pixal Per Inch, it defines how big the prints will be with a given resolution(in Pixel).

Say I have a image of 100 x 100 pixel,
If I set it to 10ppi, then the prints will come out as 10inch x 10inch, big prints but very low quality when looking at it at arm length.

If I set it to 100ppi, the prints wil lbe 1inch x 1inch, small prints but looks better at arm size.

So after all, the PPI is useful for people, who wants to make a certain size of print, to determine the image resolution should be ?

By: René

René — Mon, 08 Mar 2010 12:43:54 +0000

Hi Dave!

Did you actually read the article?
You don’t save bytes, nor do you lower the quality by using 72ppi.
All that matters is the number of pixels.

By: Dave

Dave — Mon, 08 Mar 2010 06:11:59 +0000

I think you really neglected the primary issues where ppi on the web is concerned: copyright violations and space requirements. Since virtually any image posted online nowadays can be “stolen” most uploaders prefer to (1) save bytes by reducing images to 72ppi, and (2) reduce the risk of print use by only providing lower quality images.

I know you’re primary interest is quality here, but still, these points need to be included in the discussion.