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Thread: Last question regarding DPI

  1. #1
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    Last question regarding DPI

    I recently posted a question concerning DPI and am still a little bit confused. What I am trying to accomplish is creating a drawing that will end up in a 9 inch by 7 inch book format. I am trying to figure out the dimensions of the file within ArtRage that I need to create.

    What I am unsure of is if DPI factors in when creating the demension. For instance, since I know I will be making it 300dpi for print purposes does that mean my width and height has to be 2700 x 2100 pixels? If not, what do the pixel demensions have to be.

    I just noticed that ArtRage lets you specify demensions in inches as well so that is how I will do it, BUT what if it did not, how do I know the demensions to use. I guess I am still a little confused. So let me ask it another way.

    If I created two files of 800 x 400 pixels but one was 100 dpi and the other 200 dpi does that mean the first would print at 8"x4" and the other 4"x2"? Also does the dpi factor into the size it would show up in page layout software?

    Thanks again in advance, sorry to beat this horse so hard.

  2. #2
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    DPI is only a consideration inside the program that you will be using from which to print. What you need to be concerned with while creating your image is PPI ... pixels per inch. Set your image for 100 pixels per inch for a very good quality print. So if you want a 9 x 7 print ... create a 900 x 700 pixel image in ArtRage at a minimum. Of course, an 1800 x 1400 image will work even better. Don't worry about DPI in ArtRage unless you are going to be printing directly from ArtRage.

  3. #3
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    No problem. You're correct, if you were working with pixel sizes and were printing at 300 dpi, and wanted it to be 9 x 7 inches, the correct size is the number of inches x the dpi, so as you said 2700 x 2100 pixels would be correct.

    Using physical dimensions when creating a new painting in ArtRage ( e.g. inches ) will give the same result in terms of pixels. So if you create a new painting, set the DPI to 300 and the dimensions to 9 x 7 inches, it will give you the correct number of pixels ( 2700 x 2100 )
    Dave
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    Just when I thought I had a handle on this dpi/ppi thing ... so what you're saying is that dpi does matter when you're setting up an image inside AR?

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    Thanks for the info Dave, that gels with the logic that was floating around in my head. What led me to that was that if you set the document size in terms of inches and change the DPI you will notice within ArtRage the canvas size DOES get larger as you increase your DPI. That is what had me believing DPI does effect more then just the print time process.

    I did play with toggling back and fourth between inches and pixel dimensions after I set DPI and did see what you are talking about.

    Thanks again for your help.

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    Quote Originally Posted by RobertSWade View Post
    Just when I thought I had a handle on this dpi/ppi thing ... so what you're saying is that dpi does matter when you're setting up an image inside AR?
    DPI only matters when you are setting up an image if you set image size in Inches, CM, or MM.

    If you set image size in Pixels then you get an image with that many pixels and DPI just tells the printer how densely to place them when it prints.

    If you set the image size in Inches, CM, or MM then the number of pixels allocated is calculated using the DPI calculation, you still have a number of pixels in your painting, but it's an easier way to work out how big the printed result will be.

    DPI suffers from the fact that it's easy to assume it relates to your screen when really it just tells printers how big to print stuff.
    Matt
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  7. #7
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    I submitted this post to your previous question. Hope it helps, not confuses.

    Edimus,

    For your comic strip you could work at the desired web size x 72. If your strip is to appear at 8" x 2" your canvas could be 576 x 144 ppi. That's small, so you could work in scale to that at 2x, 3x, 10x or whatever is comfortable. Of course you're saving all the time. When your ready, with the file saved, you can rescale your canvas, under the EDIT menu to the 576 x 144 ppi size, and export the image. Then close your painting without saving it, thereby maintaining the original size.

    If your image is to be printed by a commercial printer, the preferred ppi is printed size x 300 ppi. Although images can have a slightly lesser ppi, this is the industry default. Therefore an 8" x 2" image would be 2400 x 600 ppi.

    DPI and PPI are not the same, although they seem to have been used interchangeably for the last 10 or so years. No offense, but ArtRage is really talking about PPI in their "rescale" windows. DPI (dots per inch) is from the printing industry and refers to the screen values used to print images. Newspaper images used to be printed at 65 DPI and you could see the dots in the image. Magazines were printed at 133 DPI and you had to look very closely to see the dots. Fine art books were printed at 200 DPI and you had to use a magnifying glass to see the dots. PPI (pixels per inch) refers to raster images. It's possible to have a 700 ppi image destined to be printed at 133 DPI. For printing purposes, the difference between this image and a 300 ppi image is longer RIP (raster image processor) time, not quality of final printed image.

    Is this too much geek speak?

    Any ArtRagers who dispute any of my post or suggestions, please jump in. I don't want to mislead anyone.

    Mike

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