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Are Pixels square? Answered

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I'm trying to scale a graphic I downloaded from the internet. The program I'm using (HP Photosmart Studio) tells me that it's 426 x 1024 pixels, which gives me an aspect ratio of 0.42:1. But in inches, it's 5.00 x 14.22, which has an aspect ratio of 0.35:1. So either I'm blowing the math, or I'm losing my mind, or pixels aren't square. (Why, in the name of anything at all, woud pixels not be square?)

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kevinhannanBest Answer (author)2009-08-17

It depends where the pixel is - really! A pixel from a printer is different in composition and ratio and size to a pixel on a CRT/Flat screen and idfferent to a pixel from a scanner. In my mind I do not make a relationship between between different objects and their pixels. What I do is accept that for one device a certain number of pixels is optimum for the size of job in hand. So for scanning I use 100dpi for the screen and 600dpi for printing; for printing I have a chart of optimum pixel sizes for the size sheet I want to print out and for the screen I look at the size of pixels there, the smaller the better - a common screen pixel size is 0.26mm. I hope this helps and releases you from your pixel puzzlement! Good luck!

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Gorfram (author)kevinhannan2009-08-18

"It depends on where the pixel is..."

So, saying that a pixel has an aspect ratio of 0.35:1 in a given graphics program is like saying that a pound of mass is equal to a pound of weight on a given planet? Take your pound of mass from Earth to Mars and it's less than 1 lb. of weight, take it to Venus and the same lb. of mass weighs more.

Do I gather correctly that different devices (CRTs, flatscreens, printers-du-jour, etc.) have different optimum pixel sizes and aspect ratios? That would make sense, actually - rastering a cathode ray on to a phosphorescent screen would be a whole different technical ball of wax than depositing a dot of ink on paper.

Not sure I'm solidly sanguine about my pixel puzzlement yet (although I eventually was able to print out my graphic satisfactorily), but you've been a great help - thanks very much for your answer! :)

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kevinhannan (author)Gorfram2009-08-19

Shall I look for my chart of optimum pixels for printing; would that be useful for you?

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Gorfram (author)kevinhannan2009-08-19

I appreciate the offer, but I don't really do that much graphic messing about - thanks very much anyway. It's really just that I had always assumed and understood pixels as being square, erronenous though that turned out to be, and so their changing aspect ratios were badly interfering with my conceptual framework of all pixel-related portions of reality. You were able to help clear that up for me, which is a great intellectual relief.

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steveastrouk (author)Gorfram2009-08-19

YES, that's right. all visual output devices that use pixels are different.

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steveastrouk (author)2009-06-26

Pixels ain't necessarily square. Deal with it ;-) Yes, its fiendishly difficult to adjust things precisely from what you have recorded to what you want to see correctly on screen.. So, on the plus side, you ARE sane ! Steve

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Gorfram (author)steveastrouk2009-08-18

"So, on the plus side, you ARE sane !"

I always hoped that someday, somebody, somewhere would think so... ;)

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Goodhart (author)2009-06-27

You can get a sense of how it is if you can imagine making a large picture using large canon balls as pixels.

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