 Jeff |
photoshop, dpi, ppi, digital rebel Hello, I have a canon digital rebel which is 8.2 megapixels but I'm getting confused with the dpi/ppi factor when I bring my photos into photoshop. I understand that dpi is dots per inch and ppi is pixels per inch. And I understand that dpi has to do with printing. But most printers want my photo file to be 300 dpi. However, whenever I bring a photo into photoshop, the default is 72 dpi. Even if I use a lower mega pixel camera, it still comes in at 72 dpi. I dont understand why to different mega pixel cameras come in at the same dpi. And to really get me frustrated, I also read somewhere that some photo editing programs show dpi when they really mean ppi and vise-versa. Is this the case with photoshop? It doesnt seem that it would be as easy as just changing the 72 dpi in photoshop to 300 dpi because why couldnt you then just change it to 1000 dpi to have super amazing quality? So my main question is, if someone wants a photo file of 300 dpi, what do I need to do in photoshop to accomplish that? Thanks, and if this has been discussed is the past please point me to the link.
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chrisbudny.com - Chris Budny Contact Chris Budny Chris Budny's Gallery |
It is a popular topic... Search BP on DPI or PPI and you'll find some threads... (For dpi, remember 'dots' of ink; therefore primarily a printing reference.) Remember, your camera captures X number pixels, period. (Let's say a normal image comes up as 1728 x 2160 pixels = 3,732,480) Most monitors display around 72ppi. So your photo may have display dimensions of 24" x 30" when viewed in your software on your monitor. (Because 1,728 pixels across the top, displayed in 72-per-inch format = 24".) If you tell that software to reflect the image as 300ppi, the onscreen display dimensions will shrink to about 5.75" x 7.2"... yet you've not changed any underlying pixel data in your image. If your printer is capable of 300dpi output, then your 300dpi print would measure out to about 5.75 x 7.2. If you took that same original file and asked for 1000ppi, your resulting image onscreen would display as 1.7" x 2.2". (Of course, your monitor is still only capable of displaying 72ppi during all this!) If you state a certain ppi AND also specify a fixed image size (say, 300ppi, but an image size of 10" x 12", that doesn't equate naturally like the example above) your software will have to "create" new pixels out of thin air to achieve this (assuming you're increasing in image display size) and you get into a whole new topic of upsizing your files.
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Jeff |
Thanks for your great answer. I did search the other threads and I'm starting to get the hang of it. But I'm still a little confused regarding the setting in photoshop where you can reset dpi. Is that setting mislabeled? Should that setting be called "dpi/ppi" instead of just "dpi" because it affects what you see on the screen and it effects the output of the printers, correct?
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chrisbudny.com - Chris Budny Contact Chris Budny Chris Budny's Gallery |
Jeff, I think part of your puzzlement is that awhile ago "dpi" became a casual, universal term to indicate resolution of any kind. (Don't forget the siblings lpi - lines per inch, and spi - scan/samples per inch.) Sloppy use of vocabulary, sure, but it is what it is. ppi is really meant to relate to a digital image file, and dpi to refer to output resolution... but some probably argued a "dot" (as in dpi) is a good analogy for a pixel (ie, ppi) and so it sticks... confusing to swap the terms, and often, just as confusing to some, when correctly using the terms! As to your original question, to produce a file at 300 dpi... using my PSE2 software, I'd open the original file, go to Image... Resize... and in the dialog box, uncheck "Resample Image". Then in the Resolution field (which always shows me 72) change that to 300. I'd immediately see the height and width measures change (from my camera file's default of 36" x 27") to 8.64 x 6.48. Now, I've not had to actually do this for any files yet, personally---I remain in the realm of web display so far. So hopefully if I've mistated anything here, someone will come along and correct me ;)
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Karim Abiali |
Jeff, using PSE2 software that is provided with the camera, go to preference and change the settings from 72 to 300 or even you can go up to more than 2000. By default, Canon digital rebel XT import the images at 72 dpi unless you specify otherwise. Hope this helps.
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Jeff |
Thanks for all the good info. Karim, I just browsed "my programs" and I didnt see PSE2. Is there another name for the software, perhaps?
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chrisbudny.com - Chris Budny Contact Chris Budny Chris Budny's Gallery |
PSE2 is Photoshop Elements 2.0 (the "Elements" software, vs. full-blown Photoshop, is currently up to release 4.0)
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Karim Abiali |
Jeff, Chris is right PSE2 is photoshop element 2. If it is not provided with your camera, then Digital Photo Professional should be provided for sure. In this program in the preferences as well you will be able to change the dpi. I changed mine from 72 to 600, which I use now as a default. Hope this helps.
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Jeff |
Hmmm, I guess I must have misplaced the PSE2 or Digital Photo Pro. I cant set the dpi setting in full blown photoshop, correct? If not, no big deal, it doesnt take long to change it manually. Quick question...I'm using one of my pictures for a cover of a magazine which is 8.5 x 11. At 300 dpi my picture comes up short. So when I scale my picture to the 8.5 x 11 the dpi changes to around 271. It looks pretty clear to me but is that going to be a problem as it's under 300 dpi? Thanks for all your answers.
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Craig m. Zacarelli |
shouldnt be.. you can change the dpi in PS just as you change The Image size.. craig-
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Craig m. Zacarelli |
shouldnt be.. you can change the dpi in PS just as you change The Image size.. craig-
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Jeff |
But can I 'set' the default dpi to 300 instead of 72? If so, where can I do that?
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Karim Abiali |
In the dgital photo pro (it should be on the CD provided with the camera at the time of purchase)- in the preference menu, if you can send me your personal email, I can send a screenshot.
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Jeff |
I seemed to have misplaced that software that was provided with my camera so I was just wondering if you could 'set' the dpi default in full blown photoshop to be 300.
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Karim Abiali |
in PS go to edit,preferences, unit&rulers and change the setting. If you are shooting RAW, then when processing the image you can change the dpi to whatever you want.
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