does image dpi matter to web browsers?

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does image dpi matter to web browsers?

In the past I had seen occasions where images that weren't 72 dpi wouldn't show in some web browsers, primarily Internet Explorer 7. However, weird thing is, I have tested this lately and it appears that images of 300dpi are showing in IE.

Does DPI matter anymore for web? Will photos of some DPIs not display in some web browers?

+1 A:

No, it doesn't and it never matter. DPI only matters for printing.

Lie Ryan 2010-09-27 12:20:34

Incorrect. Screens have a DPI as well, although many default to 72 or other DPI setting. That said, I believe that many web browsers probably tend to ignore that setting in the images.

Arafangion 2010-09-27 12:21:48

Web browsers completely ignore DPI settings in images even when printing. The DPI values in images on the web are largely meaningless anyway (some 72, some 96, some other random values... web browsers would be crazy to treat them as accurate).

bobince 2010-09-27 12:30:57

@Arafangion: No, you are incorrect. The concept of DPI is irrelevant for images on computer screen. Screen DPI is a misnomer for a wholly different concept, screen DPI is for conceptual calculation of text size (not even image size). I'm not going to explain further, just read it for yourself http://www.scantips.com/no72dpi.html

Lie Ryan 2010-09-27 12:32:26

X11 does use DPI, although many applications do ignore them, which is unfortunate. (If applications used them correctly, perhaps we might've been able to find a generic solution that lets circles be rendered as circles, and squares as squares, rather than ovals and rectangles, without calibrating each application individually).

Arafangion 2010-09-27 13:28:51

@Arafangion: Again, it's not related to DPI at all. If you have problems with circles being rendered as ovals, it's a problem with not setting screen resolution correctly, not DPI. Let's straighten this confusion, both X and Windows only use dpi for font size calculation. There is no need for calibrating individual application if you setup your screen resolution correctly

Lie Ryan 2010-09-27 13:42:48

@Lie: So... My screen resolution has a particular screen resolution. Now, I want to render a square such that it is 3 cm in length, and 3 cm in height. How do I do this without a DPI setting?

Arafangion 2010-09-27 13:46:56

@Arafangion: You don't. Draw a 100x100 pixel rectangle and provide a visual cue that says it's 3x3cm (more often, you don't even need the cue). You only need to calculate the DPI when the user asks you to print that "100x100 pixels rectangle that claims to be 3x3 cm". On screen, the standard measurement unit is pixels, not centimeters.

Lie Ryan 2010-09-27 14:07:42

@Lie: CAD programs for civil engineering generally look *much* better if the squares and circles are accurately drawn.

Arafangion 2010-09-28 12:04:44

@Arafangion: your whole screen will look *much* better if you setup your **screen resolution** correctly. Skewed squares and rectangles is not the fault of DPI, a 100x100 pixel rectangle will look square if you use the correct screen resolution, and it will still look square when printed. Changing DPI setting does not change the aspect ratio of screen objects.

Lie Ryan 2010-09-28 23:02:33

@Lie: So... Are the pixels on a screen always square? Even for non-standard aspect ratios and netbooks?

Arafangion 2010-09-29 01:34:51

@Arafangion: No, but pixel aspect ratio is still not related to DPI, nor can it be fixed by changing the DPI; you should try finding another way out from your egregious claim that DPI causes your screen to show squares as rectangles.

Lie Ryan 2010-09-29 06:20:50

@Lie: It sounds like we have a different definition or understanding of the term "DPI" at a fundamental level. From where I stand, "DPI" means "For this inch, how many dots (ie, pixels) are there?".

Arafangion 2010-09-29 07:34:17

@Arafangion: That's where you misunderstood. The **DPI of an image** is not, in any way, related to the number of pixels the image takes on screen or to the actual size of the image on screen. Asking the DPI of an image on screen does not even make any sense. DPI is useful only when printing (or scanning), it is used to calculate the scaling of the size of image on screen (pixels/dots) to size of the image on paper (inch). A 72x72 pixels image with 72 DPI will get printed as 1x1 inch on paper. On screen, the image will always take 72x72 pixels unless you zoom.

Lie Ryan 2010-09-29 09:33:40

@Arafangion: If you have a screen that skews your squares, then you have to fix your screen resolution (and if you have the misfortune of working with non-square pixel aspect ratio, then you just tell X and it'll automatically calculate the compensating ratio, all without the need to change any applications). There is no DPI involved in all of this.

Lie Ryan 2010-09-29 09:38:08

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does image dpi matter to web browsers?

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