# Photoshop:  Determine a photo's DPI?



## themacko (Nov 22, 2002)

I'm trying to determine from a few files what DPI they are .. whatever that means.  I have Adobe Photoshop Elements 2 and I'd assume you could do it in that, but I don't know how.

Can one of you Photoshop gurus tell me how to determine what DPI the photos are?  Thanks in advance!


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## uoba (Nov 22, 2002)

Go to Image Size (I think, haven't got it on this machine), in one of the drop down menus at the top (is above or below Canvas Size).

Anyway, there you will find the resolution information (which you can change). It will either be in dots per cm or dots per inch (DPI). This is what you want.

DPI (72 dots per inch for web, 300 dots per inch for print), just in case


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## themacko (Nov 22, 2002)

Okay thanks, I found that and it tells me the photos are 180 DPI.  Does that sound right?

These are a couple of photos that are comming from my Canon S100 digital camera, I gave some photos to a friend who's a graphics design major and she told me to make them 300 DPI next time.

I didn't know if this was a setting on my camera that I have to use or not ...


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## Sogni (Nov 22, 2002)

72 dpi is usually what web and screen graphics usually are, concidered "minimum resolution" altho I've seen pictures of less resolution *shudder*. Not recomended for print.

180 is what my digital camera takes pictures at, altho it does higher res - I've never tried it because it fits less pictures into the memory card. See if your camera has the option of taking larger pictures.

300 dpi is optimal for graphic editors and for print as one can do more at photo-realistic quality. There are tricks to increase the resolution of lower quality graphics (but the ones I know requier the full version of Photoshop and some $).

You can also bump up the res in Photoshop, in the full version of Photoshop (7), it's in Image/Image Size from the menu (never used Photoshop Elements). BUT, this is NOT recommended because the quality isn't as good. Try to bump up the resolution in your camera first if you can.


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## goynang (Nov 22, 2002)

Manually changing the resolutuion to a higher value isn't always too great a solution. Photoshop (or whatever) has to basically guess the missing data and so quality can become a problem.

Also, sometimes the actual physical dimensions of the image can be more important. For example a 150dpi picture used at 50% of its size (effective resolution = 300dpi) in a page layout application is better than a 300dpi picture used at 200% of its size (effective resolution = 150dpi). Digital images don't really have a 'set' DPI value until you actually print/view them at a given size. The DPI value in Photoshop or whatever is kind of misleading if taken on its own.

In short set your digital camera to as high a res' as you can and don't over compress the images via JPEG. If that's not good enough then there's not much more you can do anyway!


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## themacko (Nov 23, 2002)

Okay thanks for the explainations, that does make more sense.  But riddle me this, my camera has 3 quality settings; small, large and super large.   I have been using the large format simply because it's the highest quality you can go while still using 'automatic' settings.  For example, taking a picture in super large requires you to set the aperture and white lighting stuff.

Anyhoo I took two pictures of my desk, one in large and one in super large.  The large was 568k off my camera and the super large was 1.6 mb.  Both pictures are 1600x1200 and 180 DPI.  So, why is the SL almost 3x fatter (file size) than the large?


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## Tigger (Nov 23, 2002)

The super large file size often is not compressed. You can see the difference in the little details of an image. Try taking a picture of something with little details, for example take a picture of a landscape with grass on it with the two qualities.
The super large will be better for the little details, as the compression makes the picture a little blurry for the compressed quality. 
But often, the difference is so minimal that the compressed quality will be enough.

DPI is not so important fo rimages as some people think. The absolute pixel count is important. A image with 1600 x 1200 pixels can be in 300 dpi or 150 dpi, what doesn't make any difference in the quality of the image.

An image with 300 dpi and 800 x 600 pixel doesn't contain as much information as an image with 1600 x 1200 with 150 dpi. In fact, the second picture will be better for printing. But you will have to scale the image in the layout program to 50%, to get its dpi to 300 to print right.


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## MacLuv (Nov 23, 2002)




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## MacLuv (Nov 23, 2002)




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## Jason (Nov 23, 2002)

you can generally and i say generally because its not always a good thing

increase the size of the image about 60dpi and get away with it, but like i said its not always a good thing to do, and it depends on how good the output is etc

i generally shoot 8x10's that are 225, i increase them to 300 and they are usually fine (useful for if they need to go into a composition at simliar size)

oh and if you are printing out of an inkjet, you can probably get away with 180, because an inkjet from what i know likes multiples of its dpi, so it likes files that are 180, or if possible 360, but that was something i heard a while back and im not sure if its true *shrugs*


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## Sogni (Nov 23, 2002)

This helps:
http://www.lizardtech.com/solutions/photo/

Altho I think you need the full version of Photoshop.


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