I have several tifs that has a resolution of 400 dpi but is at 1024X700 pixels. Since dpi really has no place in the video world, how can I convert the dpi down to 72 to increase my pixel width and heighth?
I’m sure there is a certain amount of math that needs to be applied. I just don’t know how to do it.
Thanks,
Scott
Basically just ignore the DPI. There’s no converting involved really, you have 1024x700 pixels to work with. You can resize your image in PS but you’ll just change the DPI to 72 and re-enter the dimensions as 1024x700.
Aye, ignore the DPI, but if you happen to have a supervisor or client who’s insisting that 72 dpi is a magic number:
Image > Image size… uncheck “Resample Image,” and change the Resolution. The only thing that will change is the metadata and the result of pushing the “Print Size” button; the image itself will be identical.
I’m not insisting that 72 is a magic number, it is the magic number. I can import any dpi but I but video will convert it to 72 no matter what.
The question is whether not I can have a 400 DPI image at 1024X700 and make it larger because of the DPI. I thought lowering the DPI could make your image larger in pixel size (heightXwidth.) I know it works the other way around.
In 3DS Max you cannot make a resolution higher than 72 dpi. So in order to make something for print, you had to render at something very large, take it into Photoshop, and change the 72 DPI to 300 and your pixel dimensions (height and width) would lower.
Nope, pixels are pixels and you have the same number no matter what the resolution/DPI. If you want to know how big your image can print, take the pixel dimensions and divide by 300, i.e. if an image is 600x900 it will print at 2" x 3" at 300 DPI. Works in reverse if you’re trying to figure out how big to render an image you want to print, desired inches * 300 = pixel height/width for that side. You can always print at a lower DPI as well but you’ll lose some quality.
If you don’t want the pixels to adjust when you change the resolution in Photoshop uncheck “Resample Image” as mentioned.
hmmmm, I understand. I just don’t understand why you can work it in reverse but not the other way around? It should work both ways, no?
No, because you’re not changing the actual dimensions of the image, just the size (DPI) that it’s printed at, or more accurately is interpreted at.
Think of it like this: You have a a piece of graph paper and draw a square that’s 10 x 10 on that grid:
Now if you took another sheet of graph paper that had smaller squares on it and drew the square again the exact same size, the square hasn’t actually gotten any bigger but it contains more grid units:
When you change the DPI of an image in Photoshop with “Resample image” unchecked that’s exactly what you’re doing, you’re just changing the way that box is described. The actual pixel size of the box doesn’t change. If you were to have “Resample image” checked when you change the DPI then that would alter the actual pixel size of the box and your image would scale because you’re altering the number of pixels in width/height.
That make sense?
Whenever a client of mine keeps bugging me about dpi and images meant to be used for either video, or the web, I send them a 1 pixel image at the dpi they requested (i.e. mostly 300, 600 or 1200 dpi).
Watch their face as it shows denial, rage, sorrow and acceptance in a blink of an eye 
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