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DL size in pixels?

     
5:36 pm on Aug 19, 2008 (gmt 0)

5+ Year Member



Hi all,

Simple question really.

The paper size of DL (220 x 110mm), whats that going to be in pixels?

If i go to photoshop, new, select them sizes in mm, and then press pixels, gives me 624 x 312 pixels, is that right? It doesn't look right on the screen...

This is eventually for printing, so does it need to be bigger?

thanks

:)

5:42 pm on Aug 19, 2008 (gmt 0)

10+ Year Member



Change the Resolution to 300 Pixels Per inch, and you should get the correct print size.
9:06 pm on Aug 19, 2008 (gmt 0)

5+ Year Member



ah..cool

thanks alot!

:)

10:35 am on Aug 21, 2008 (gmt 0)

WebmasterWorld Senior Member 10+ Year Member



Simple question really.

Not really and is probably one the harder things to sink in for many people.

A pixel has no dimension, its just a single square of color. For example if you have your resolution on you monitor set at 800x600 you have 480,000 pixels displayed. Change it to 1600x1200 and now you have nearly 2 million pixels displayed in the same physical space.

When you print an image on a physical surface like paper you need to give the pixel a dimension. Enter DPI(or resolution but I'll stick with DPI) which acts as "translator" between the digital world and physical world. DPI sets the scale of an image. For example if you have an image that is 600x600 pixels and set it to 100 DPI the resultant image by default will print at 6 inches by 6 inches. Imagine each of these periods represents 100 pixels and the length is 6 inches on each side:

. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .

If you set it to 200DPI then it will print out in half the area, each period now represents 200 pixels:

. . .
. . .
. . .

The size of the image in pixels has not changed you're just printing more pixels in a smaller space. If you're lost at this point an easy way to comprehend this is to take your image and save two versions. Make one 100DPI and the other 300DPI, DO NOT change the pixel size you just want to change the DPI and the DPI alone.

Create a web page with both images, they will display exactly the same size. The reason for this is because a web browser displays images at their pixel size. In fact these images are exactly the same images pixel for pixel and will be the exact same file size on disc as well. The only thing that is different is the DPI setting, since the DPI value is just "translator" to the physical world it is pretty much useless for images that will only ever be displayed on a computer.

On the other hand if you use these images in an application like Word you'll get two different sized images because the "canvas" is representing a piece of paper which has physical size. Word will use the DPI information to scale it.

As far as printing goes for the best results 300DPI is about as good as its going to get. Anything higher and the human eye loses the ability to detect anything. So if you set your 624x312 image to 300DPI by default you can print a nice picture a little bit bigger than a postage stamp. ;P

Assuming you have a large source image resize as inches and set the DPI simultaneously. For example if your target size is 6 inches by 4 inches you'd resize to that and set the DPI to 300 at the same time. The resultant image would be 1800x1200 which of course is very large for an image on the internet but will print by default at the exact scale you wanted.

----------------

Notes: I don't know how this works with the metric units and used DPI(dots per inch).

2:11 pm on Aug 23, 2008 (gmt 0)

5+ Year Member



ah...nice bit of info there

thanks

:)

 

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