Inches, Dots, Points, Pixels, DPI, PPI...

[Guest]

Hello everyone,

I write here today because I'm completely lost with all those units.

I'm trying to do something that would appear to be simple but I'm completely lost even after reading a few webpages about it.

I want to create an image of a certain size (12 inches x 18 inches) at a certain resolution (300 dpi) using either PhotoShop or Illustrator, preferably PhotoShop since Illustrator is even more complicated.

So I create a new document and specify :

     - Length: 12 inches

     - Height: 18 inches

     - Resolution: 300

Then what I want is simple : write a letter and give it a size in points so that the letter takes either all the width of my calk or all the height of my calk. I don't want to use the transform button. Until now the better solution I've found is to place the text at the center of my calk and then scale it with ALT + SHIFT which is exactly what I just said I don't want to do, so that it respects one condition mentioned above, but it's not accurate and either way I don't get where the resulting size in "points" comes from for the text.

I tried the Google converting tool to convert from one unit to another, I've used the NinjaUnits converter to transform inches into pixels and then pixels into points... but whatever I do I can't find where this value in points comes from...

Can you please explain if it's actually possible to write some excel sheet where I can just give the size of my document in inches and it automatically prints in a next cell what should be the size in "points" so that the text either has a "perfect width" either a "perfect height" and by that I mean that the text width or height is equal to the calk width or height.

Thanks for your advices !

[c.pfaffenbichler]

I want to create an image of a certain size (12 inches x 18 inches) at a certain resolution (300 dpi)

Resolution of pixel images is given in ppi, dpi refers to halftone screens employed in printing.

The point size in font size does not necessarily describe the height or width of any letter in that font, so you may have set yourself up for frustration.

Quote from

Point (typography) - Wikipedia

In digital type, letters of a font are designed around an imaginary space called an em square. When a point size of a font is specified, the font is scaled so that its em square has a side length of that particular length in points. Although the letters of a font usually fit within the font's em square, there is not necessarily any size relationship between the two, so the point size does not necessarily correspond to any measurement of the size of the letters on the printed page.

What do you mean by »calk«?

[Derek Cross]

"dpi refers to halftone screens employed in printing." This is not exactly accurate:

DPI stands for dots per inch, which is a useful terminology for desk-top printers. Halftones used in commercial printing, use the terminology LPI (meaning Lines Per Inch) also known as line screen (not to be confused with the screen printing process). Typically 133 LPI is used for litho printing on coated stock. You normally have two pixels per line screen (but you can get a way with less), That's why the rule of thumb is 300PPI for images that are to be printed on commercial litho presses on coated stock. Large posters that are to be viewed from a distance can have a much lower resolution, as can those that are printed on web presses on newsprint (typically 85LPI).

The size of a typeface (without leading) is measured from the top of the ascenders to the bottom of the descenders. The X height (which is the height of a lower case x) varies from typeface to typeface. A small x-hieght makes the typeface appear larger and conversely a large x-height makes it appear larger. Both faces below are the same size (48pt).

[c.pfaffenbichler]

"dpi refers to halftone screens employed in printing." This is not exactly accurate

Right you are, thanks for pointing out my mistake.

dpi are used to describe, for example, the native resolution of a plate-setter or the number of dots per inch in a digital print.

[Norman Sanders]

If you are truly "completely lost by all those units", until you feel comfortable with it all, consider the temporary fix and use one common measure within Photoshop:

You may specify image size in millimeters.

You may specify type size in millimeters, as well, by going to Preferences > Units & Rulers > Type: Millimeters

[mglush]

Hi!

It's unclear what you are trying to do...when you say letter, do you mean a body of text in paragraph form like a written letter? Or, do you mean one character (letter)? And, I also would like to know what a calk is?

One thought--if you are importing an image of text, then you might have problems with clarity when you resize the image. But if you generate the text in Photoshop, since the text is vector, when you resize it (make it larger) it will still be sharp and can fill your space. If you are generating text in Photoshop, the point size of the text won't really matter.

Would love to help, but need more information!

Michelle

[Derek Cross]

As he has access to Illustrator, he'd be better off using that, if he's only having text in his image.