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DonPittman

Pix calculations

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So me being a in/cm kind of guy. I don't understand pixels setting and how they work. I can count on someone here to explain them to me.

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Pixel is the smallest unit of the device.

Just imagine the paper and you putting dots on it next to each other. (Without overlapping).

One dot is one pixel. Since pen has fixed size you can fit so many dots per inch. Its called DPI.

Dots per inch.

Your monitor has 72 DPI.( standard size, or 96 DPI on newer monitors). So any picture 72 pixels wide will be 1 inch wide on your monitor.

Your printer has 600 DPI. So same picture when printed will be only 0.15 inch wide.

Normal pictures (like photographs)done with pixels. Vector images done with lines in inches (or centimeters)

So vector images will look the same regardless device they are looked at.

Normal pictures needs to be programmatically (mathematically) shrinked/stretched in order to look the same on different devices ( monitors/printers).

Hope that helps.

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Just to add, Imagine your monitor has 1024 pixels width and 728 pixels high.

So normal picture (photograph) is a command to paint pixel with coordinate (3,5)(3,6),(3,7),...(3,77) with color green.

So you get a picture of a green line that visually is 1 inch long ( on monitor with 72 DPI, hence from 5 to 77, 72 pixels = 1 inch.).

But if you try to print it, since printers usually have much higher DPI, those commands will produce a green line that is visibly much shorter than 1 inch.

PS: modern printing software is smart enough and extrapolates picture so the final result on a printer has same look of green line 1 inch long.

Vector pictures are a bit different. Vector graphics are commands to draw green line from position (0.5 inch, 0,5 inch) to (0.5 inch, 1.5 inch)

Those commands will produce green line 1 inch long no matter which device you using them on.

And that is why vector images scale so easily. You just multiply all coordinates by needed ratio.

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I'm having trouble with my printer. If a scan a design it never comes out at the same size when I print it. The page setup says its at 100%. Could it be the dpi I'm using when I scan the graphic? I'm new to this so please bear along with this newbie! Thanks

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Printers are often a PIA to get perfect. I use epson printers and they work great. What printer are you using and what software? Hard to be helpful with the information you have presented. 

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I have an HP office jet 6700, HP Scann 4.0.50, currently have only Microsft word to design in. No real design programs at this time. Don't know if I have the scanner setup wrong, choice of presets wrong or something else. I've experimented changing the presets in the scan program but nothing comes out the same size as the scan when printed. Any suggestions.

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word kind of sucks too. Almost no control and it's diabolical sometimes. I am an Adobe Illustrator user and find myself usually coming home to AI to build anything tricky like a flyer or card. Just so much more control over layout and all involved. 

 

You might try Gimp, It's a pretty good (and free) photo program similar to Photoshop. 

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Thank, I'll try that, signyouup. Wild goose, I'll look up Gimp. Thanks again! Since everyone is so helpful, I thought I'd pay it forward with my experience in glass etching. Please read my post in general discussion, glass etching if your interested in learning about processes I used in my work.

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