Very large fine JPEGs have a max of 72ppi?

[Persephone]

Hey...I just got a 20D, and I shoot on the very fine Large JPEG option. Today I noticed that it only shot 72ppi...comapred to my old Nikon P&S, which had 300ppi. Is this the top limit? I tried RAW and found that it came out to be 240ppi, but that's still not as high as 300. Is there some kind of secret function that I'm not aware of, or is this reality? I would have probably moved to RAW anyway but I didn't want to be pushed for this reason.

[cosworth]

ppi is a ratio. no limitation. Just change your raw viewer to 300 or 240 or whatever if you really need to see it.

You really have nothing to worry about here.

[Persephone]

Okay, I just saved my first JPG from RAW and it is 300ppi. That's good. What about my first question?

[Eaton Photos]

ppi is a ratio. no limitation. Just change your raw viewer to 300 or 240 or whatever if you really need to see it.

You really have nothing to worry about here.

+1.... Almost all DSLR's default to 72ppi/dpi... You can easily resize your images to 300 ppi if you need it. The 20D comes with DPP. You can download the recent 3.4 update HERE (http://www.usa.canon.com/consumer/controller;topic=609.msg7296?act=ModelInfoAct&tabact=DownloadDetailTabAct&fcategoryid=314&modelid=10464)

If you need to resize your images, you can do batches in DPP, or other batch editing programs.

[Bruce_B]

Okay, I just saved my first JPG from RAW and it is 300ppi. That's good. What about my first question?

That number means nothing. Change it to whatever makes you happy.

[liquefied]

Ppi dictates document size. It's meaningless if you aren't printing. You can have it be whatever you want, just change it in the image size dialogue in photoshop.

[Bruce_B]

+1.... Almost all DSLR's default to 72ppi/dpi... You can easily resize your images to 300 ppi if you need it. The 20D comes with DPP. You can download the recent 3.4 update HERE (http://www.usa.canon.com/consumer/controller;topic=609.msg7296?act=ModelInfoAct&tabact=DownloadDetailTabAct&fcategoryid=314&modelid=10464)

If you need to resize your images, you can do batches in DPP, or other batch editing programs.

Changing that number doesn't resize or change the image in any way. It's just metadata.

[prime80]

The ppi indication is irrelavant. It's an arbitrary number assigned as the default by Canon for some reason. Your raw image is no different, it's just that the raw converter is set to assign 240ppi as the default. If you do a forum search for PPI, you'll see MANY posts explaining this in great detail.

[basroil]

For an partial answer to your question, P&S cameras assume 300dpi because the average consumer photo printer can only print that high of resolution. for slrs, it's as arbitrary as the photo review zoom feature (more than " 100% " of a quarter sized jpg...)

[Bodog]

If you take a 72 ppi image and resize it to 300 ppi, it does resize the image. It does not change the dimensions, but it does increase the pixel data. So in essence, we are both correct, however, you are just playing on my words. :cool:
NO, NO, NO, NO, NO

[CyberDyneSystems]

That was "re-sampled" which created interpolation, too much was changed, not just the PPI but also the number of pixels.

If you do not force "re-sampling" (by unchecking it in the PSCS dialog box) then nothing on the image changes at all.

The only reason any changes were made was due to having re sampling checked, it was "re sampling" that altered your image, not changing the DPI.

[CyberDyneSystems]

http://photography-on-the.net/forum/showthread.php?t=83445

[blinded]

Yeah, if you interpolate an image, pixels will be added, but if you don't do that, the amount of pixels stays the same, it's just as if you're stretching or compressing the pixels when printed.

[Bruce_B]

I wish they wouldn't even put DPI in the file. It would save a lot of confusion. Or better yet, they should use 2400 as the default so everyone thinks their new camera is so much better than their old one :lol:

Of course then Nikon would change theirs to 3000 :rolleyes:

[Persephone]

I know this is old, but I just found out today that everything is arbitrary. Or, I learned what the cropping tool is all about. I was interested in using a photo lab and all my prior Nikon prints were rated 2 out of 4 bars for viability of 20x30 poster prints. So when I got the Canon, I thought it would be totally awesome. It was only 3 out of 4 bars and the 72dpi looked worse than the Nikon's 300dpi.

Then I used crop, 10x8. To those that know about aspect ratios, you're probably chuckling. The print came back with white strips on the sides. I just found out now that 8x10 is a 4:5 ratio whereas 20x30 is a 2:3 ratio. It's like the reverse of my old prints, where the sides would be cut off when I made 8x10s.

Today, to recrop, I put 30x20 in the crop window. The subsequent file was 21MB. i uploaded it ot the same lab - and volia - all prints, including up to 30x60, are now at 4 out of 4 bars.

[Irreverent]

For those that struggle over this - ppi has nothing to do with how many pixels are in your image. a 10mp image at 72ppi and a 10mp image at 300ppi are EXACTLY the same image and will display exactly the same on your screen, because your monitor has a fixed ppi value (in the past it was 72 ppi, but now is probably closer to 96, but this is why we have the 72 ppi option). This is to say, if your monitor is physically designed so that 72 pixels are squeezed into one inch of horizontal space (72x72 for a 1 inch square), then an image with a horizontal resolution of 720 pixels will always be 10 inches wide on your screen when viewed at 100% REGARDLESS of the ppi metadata associated with the image.

This ppi value only comes into play when printing, because printers can render images out so that each pixel represents a varying number of dots per inch. At this stage of the process, there is a big difference, in terms of image size and image quality, between a 4000x3000 pixel document being printed at 72 dpi or 300 dpi, but while that image remains inside your computer, or for distribution on the web, the ppi setting is totally irrelevant.