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FORUMS Post Processing, Marketing & Presenting Photos RAW, Post Processing & Printing 
Thread started 04 Jul 2005 (Monday) 12:47
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Crost_10D
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Jul 04, 2005 12:47 |  #1

Hi guys. I was suprised a little when found out that 20d has 72dpi vs 10d 180dpi in image. Is true or may be it is changable. I do know how it works but still wanted to ask pros out there if it matters?




  
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CyberDyneSystems
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Jul 04, 2005 12:50 |  #2

This setting "DPI" is meaningless in a digital image.

You can change it to whatever you want to in PS and no actual changes will be made to your images.
Feel free to set it to 3000DPI.. it will not change a thing ;)


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Jul 04, 2005 12:52 as a reply to  @ CyberDyneSystems's post |  #3

CyberDyneSystems wrote:

Feel free to set it to 3000DPI.. it will not change a thing.

And then you can print your own postage stamps.;)


griff2;)

  
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CyberDyneSystems
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Jul 04, 2005 12:57 |  #4

:rolleyes: .. O-kay.. well if you print using the DPI settings.. then it will effect the prints.. ;)
(But you'd rarely want to print @ 72 DPI either would you? )

So let me repharase.. changing DP settings on a Digital image will not effect the Digital Image.. it will ONLY effect the print out put IF you use the DPI setting to scale your prints.

Whatever the cameras defaults are make no difference as you would rarely if ever use the cameras defaults to actually make the prints.. you would specify the DPI to suit your own printing needs..

If you need postage stamps... then feel free to set it to 3000 DPI ;) :lol:


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Crost_10D
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Jul 04, 2005 13:20 |  #5

I know all that guys... but why in the world 10d had 180 and 20d 72? oooo that's the question anybody hardly can answer right?




  
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Hellashot
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Jul 04, 2005 14:12 as a reply to  @ Crost_10D's post |  #6
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Crost_10D wrote:
I know all that guys... but why in the world 10d had 180 and 20d 72? oooo that's the question anybody hardly can answer right?

It's the default setting for the image when opened. It'll give the "image size" as something huge - like 48x60". 72DPI is a standard DPI for web images. All that matters is now many pixels you have and what size you want to print at. A 6MP Drebel image at 300DPI (standard photographic quality) is 6.8"x10.2"


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Jul 04, 2005 14:14 as a reply to  @ Crost_10D's post |  #7

Crost_10D wrote:
but why in the world 10d had 180 and 20d 72?

Probably because back when the 10D was in production, everyone said, "Why is the 10D 180dpi while other cameras are.......", so for the newer models they decided to go with the more common default resolution of 72 dpi which is also the default dpi of most graphics programs, the standard web graphics resolution, and the old standard for computer monitors as well. Although today most monitors are 90-120 dpi or even higher on some smaller devices.


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Jul 04, 2005 14:19 |  #8

http://www.scantips.co​m/no72dpi.html (external link)
Good reading for 72 dpi fans :)


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CyberDyneSystems
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Jul 04, 2005 14:51 |  #9

:lol: lol: Oh.. that's good!


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Jul 04, 2005 14:57 as a reply to  @ pcasciola's post |  #10

pcasciola wrote:
Probably because back when the 10D was in production, everyone said, "Why is the 10D 180dpi while other cameras are.......

:lol:
This is more thasn just funny..

Really .. the image almost has to contain some sort of DPI setting... I suppose it could be zero.... ???

But really.. what setting should it be?

No default will ever be correct except by some accidental miracle at printing time.. so no matter what number Canon chooses as default it will allways be wrong 99.99999999999999% of the time.


Mind you.. I'd rather print at 180 than 72 ;)


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elbirth
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Jul 04, 2005 18:14 |  #11

ok, I've got a question since this has been brought up, it's confused me somewhat for a while....

I know DPI is only relevant for printing pictures, but what about PPI (Pixels Per Inch)? This is what the 20D defaults to for JPEGs it saves. In Photoshop, if you leave Resample checked and change the PPI, the pixel number changes (of course) but the document size in inches stays the same. However, if you turn of resampling, the document size in inches changes.

I don't understand this.... a while back I did a shoot for a campus group's CD cover they were doing... I gave them the JPEGs because they were having someone edit them. They called and said they were only 72 PPI and requested 300... so I just processed the RAW photos I took and gave it to them. I asked around and I was told that I could just change that in Photoshop without needing RAW, but doesn't that change the document size?

I'm confused.....


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Jul 04, 2005 18:34 as a reply to  @ elbirth's post |  #12

elbirth wrote:
ok, I've got a question since this has been brought up, it's confused me somewhat for a while....

I know DPI is only relevant for printing pictures, but what about PPI (Pixels Per Inch)? This is what the 20D defaults to for JPEGs it saves. In Photoshop, if you leave Resample checked and change the PPI, the pixel number changes (of course) but the document size in inches stays the same. However, if you turn of resampling, the document size in inches changes.

I don't understand this.... a while back I did a shoot for a campus group's CD cover they were doing... I gave them the JPEGs because they were having someone edit them. They called and said they were only 72 PPI and requested 300... so I just processed the RAW photos I took and gave it to them. I asked around and I was told that I could just change that in Photoshop without needing RAW, but doesn't that change the document size?

I'm confused.....

The only correct way to refer to image resolution is PPI - pixels per inch, it's completely unambiguous. DPI was originally "dots per inch" and then became either that or "droplets per inch" referring to inkjet printers. So you can print a 300 PPI image on an inkjet printer at 360, 720, 1440 or 2880 dpi (as examples) and it'll be the same size, but with increasing quality - DPI should be restricted to describing printer dot/resolution capabilities.

The resample checkbox allows you (to decide if you want) to change either the document size or the file size depending on whether it's unchecked or checked, respectively. If, for example, you have a picture at 4x5 inches at 300 pixels per inch (1.8 megapixels) and you change the resolution to 72 pixels per inch, you either get a 16.66 x 20.8 inch image (unchecked so the image is still 1.8 MP) or a 4x5 inch image at 72 pixels per inch with just 0.1 megapixels (checked - you just lost most of the information in the image! Perhaps that's why they didn't like the 72 dpi images.)


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SkipD
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Jul 04, 2005 18:38 |  #13

For all practical purposes, DPI and PPI are one and the same thing.

If you had edited a .jpg file in Photoshop and resaved it, you would have lost some of the original file's quality. A .jpg should be only the final product rather than an intermediate file type. I do all my editing in .TIF or .PSD formats, and when all is done I might save the results to a .jpg if there is a need to do so.


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Curtis ­ N
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Jul 04, 2005 18:49 |  #14

CyberDyne has said all that needs to be said, but if you don't believe him, here is an excellent article by Bob Atkins that helps explain DPI, PPI, etc.
http://www.photo.net/l​earn/resize/ (external link)


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Jul 07, 2005 12:24 |  #15

Ok,

So when you open a RAW file and save to Tiff in Adobe Camera Raw what settings do you use?
It gives you the option to set file size in pixels x pixels and DPI.
I normally use the 8 megapixel size (20D) at 300 dpi.

If i choose a larger pixel x pixel size does this resample the image to make it bigger?


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