Resolution...yes this topic again...

Mike Lane · May 24, 2005

Sorry, just wanted to clarify something (please don't chastize me for not searching thoroughly, I searched a bunch but didn't find an answer to my question). What resolution do you guys upload your images to Smugmug? I've been using ACR to convert them to 300 DPI but I think that may be unnecessary. Here are my thoughts.

1) My 20D images are a max of 3504 x 2336 regardless of how many pixels per inch ACR defines them to be. So this isn't an increase or decrease in resolution per se.

2) The web uses 72 dpi which means that my 3504 x 2336, 300 dpi originals look much smaller on the web than they would if they were saved at 72 dpi (which could be an issue for those who want to investigate the images more closely).

3) EZ prints is going to change all of this prior to printing anyhow depending on the print size chosen by the customer. Worse, maybe the ACR to 300 dpi that I did may cause some degradation in quality when EZP does their thing depending on the print size.

My question is should I upload at 72 dpi, or moreover does it matter at all?

jh4wvu · May 24, 2005

You might want to check out the discussion at http://www.dgrin.com/showthread.php?t=10845 I was asking a similiar question trying to figure out what people do before uploading to Smugmug. There are a variety of answers.

I think the conclusion was --- it doesn't matter since EZprints will make the appropriate adjustments as long as the images have the adequate resolution for the print that is being ordered.

I use a 10D and just upload my images directly to Smugmug. I generally shoot jpg at the highest settings. When I open an image in Photoshop it shows the image at 3072 x 2048 and 180 dpi.

Hopefully this will get you in the right direction.

Mike Lane · May 24, 2005

jh4wvu wrote:

You might want to check out the discussion at http://www.dgrin.com/showthread.php?t=10845 I was asking a similiar question trying to figure out what people do before uploading to Smugmug. There are a variety of answers.

I think the conclusion was --- it doesn't matter since EZprints will make the appropriate adjustments as long as the images have the adequate resolution for the print that is being ordered.

I use a 10D and just upload my images directly to Smugmug. I generally shoot jpg at the highest settings. When I open an image in Photoshop it shows the image at 3072 x 2048 and 180 dpi.

Hopefully this will get you in the right direction.

That was the one topic that I read entirely. It didn't really satisfy my questions actually.

On another note, your 10D takes 180 dpi jpgs? I thought the only resolution you could shoot jpgs was 72 dpi (at least on the 20D).

jh4wvu · May 24, 2005

Mike Lane wrote:

That was the one topic that I read entirely. It didn't really satisfy my questions actually.

On another note, your 10D takes 180 dpi jpgs? I thought the only resolution you could shoot jpgs was 72 dpi (at least on the 20D).

I did a search on DP Review in the Canon 10D/20D Forum and found a ton of info on the 180 vs 300 (Nikon) vs 72 dpi/ppi. The direct URL to the search results is http://search.dpreview.com/forums/search.asp?query=180+dpi&forum=1019

There are definitely different opinions on what the dpi should be set at when printing. I for one leave it alone for most print jobs unless I am doing any editing or special size.

This seemes to be a topic that is hard to explain and sometimes hard to understand. Everyone seems to have an opinion.

Mike Lane · May 24, 2005

jh4wvu wrote:

I did a search on DP Review in the Canon 10D/20D Forum and found a ton of info on the 180 vs 300 (Nikon) vs 72 dpi/ppi. The direct URL to the search results is http://search.dpreview.com/forums/search.asp?query=180+dpi&forum=1019

There are definitely different opinions on what the dpi should be set at when printing. I for one leave it alone for most print jobs unless I am doing any editing or special size.

This seemes to be a topic that is hard to explain and sometimes hard to understand. Everyone seems to have an opinion.

Okay, more research has led me to conclude that in the absence of resampling, the ppi number is merely a placeholder and further that jpgs right out of the camera are indeed 72ppi.

My question then is does the ACR 3 resample raw images when you save at a higher ppi? My guess is no since the resulting jpgs aren't massive but one never knows.

onethumb · May 25, 2005

Mike Lane wrote:

Okay, more research has led me to conclude that in the absence of resampling, the ppi number is merely a placeholder and further that jpgs right out of the camera are indeed 72ppi.

My question then is does the ACR 3 resample raw images when you save at a higher ppi? My guess is no since the resulting jpgs aren't massive but one never knows.

I'm not quite sure who came up with the "JPEGs are 72 dpi" idea, but it's just not true.

JPEG's don't have a "canvas size", and thus, have a variable dpi range. They only have a raw pixels count ("resolution"). Here are a few examples to explain what I mean:

- If you have two monitors, one a 17" at 800x600 and one a 24" 1920x1200, and you display the photo right off your camera, it will look like it's a different physical size ("inches" or the "i" in dpi/ppi), but it's exactly the same number of pixels. Thus, it's dpi is variable. It may be 50 dpi on the 17" and 120dpi on the 24" monitor.

- If you print out a print from the JPG without any resizing, say on your bubble jet at home, and print a 3x5" and an 8x10", again, you have a disparity. The exact same number of pixels were used to create both images, but they're clearly different physical dimensions ("inches").

Other image formats, like PSD, allow you to specify a "canvas size" independently of "resolution" and suddenly dpi/ppi makes sense. But JPEG doesn't fall into this category.

As for what you should do in your workflow, that's simple: DO NOT RESAMPLE YOUR IMAGE.

- Most resize algorithms aren't very good. Photoshop, especially, has horrid resizing algorithms. EZ Prints does a much much better job.

- EZ Prints has a variety of printers and they all use different fixed dpi values. Depending on the print type and size chosen, they may print at 200, 254, or 302 dpi. Two resampling stages is far worse than one, so you'll actually be damaging your print if you resample to 300dpi @ 10x15 and they then resample back down to 254 dpi.

Hope that helps!

Don

Mike Lane · May 25, 2005

onethumb wrote:

I'm not quite sure who came up with the "JPEGs are 72 dpi" idea, but it's just not true.

JPEG's don't have a "canvas size", and thus, have a variable dpi range. They only have a raw pixels count ("resolution"). Here are a few examples to explain what I mean:

- If you have two monitors, one a 17" at 800x600 and one a 24" 1920x1200, and you display the photo right off your camera, it will look like it's a different physical size ("inches" or the "i" in dpi/ppi), but it's exactly the same number of pixels. Thus, it's dpi is variable. It may be 50 dpi on the 17" and 120dpi on the 24" monitor.

- If you print out a print from the JPG without any resizing, say on your bubble jet at home, and print a 3x5" and an 8x10", again, you have a disparity. The exact same number of pixels were used to create both images, but they're clearly different physical dimensions ("inches").

Other image formats, like PSD, allow you to specify a "canvas size" independently of "resolution" and suddenly dpi/ppi makes sense. But JPEG doesn't fall into this category.

As for what you should do in your workflow, that's simple: DO NOT RESAMPLE YOUR IMAGE.

- Most resize algorithms aren't very good. Photoshop, especially, has horrid resizing algorithms. EZ Prints does a much much better job.

- EZ Prints has a variety of printers and they all use different fixed dpi values. Depending on the print type and size chosen, they may print at 200, 254, or 302 dpi. Two resampling stages is far worse than one, so you'll actually be damaging your print if you resample to 300dpi @ 10x15 and they then resample back down to 254 dpi.

Hope that helps!

Don

That does help, but I just have one last question. Does setting a ppi value in ACR resample the image?

Mitch · May 25, 2005

onethumb wrote:

As for what you should do in your workflow, that's simple: DO NOT RESAMPLE YOUR IMAGE.

- Most resize algorithms aren't very good. Photoshop, especially, has horrid resizing algorithms. EZ Prints does a much much better job.

- EZ Prints has a variety of printers and they all use different fixed dpi values. Depending on the print type and size chosen, they may print at 200, 254, or 302 dpi. Two resampling stages is far worse than one, so you'll actually be damaging your print if you resample to 300dpi @ 10x15 and they then resample back down to 254 dpi.

Hope that helps!

Don

I have to tell you folks. I knew onethumb was full of it on this one! So I set out to prove him wrong. What I really did was simplify my work flow. NO MORE RESIZING FOR ME. Couldn't be happier with my print, well I could be but that has nothing to do with resizing or not (just need to take better pictures

).

Just sticking my nose in.

Mitch

mercphoto · May 25, 2005

Mike Lane wrote:

That does help, but I just have one last question. Does setting a ppi value in ACR resample the image?

Are you talking about Adobe Camera RAW, or Photoshop? ACR is CREATING the image from the RAW file. Thus its not a re-sample, its a first-creation.

From within Photoshop itself, if you go to Image Size and type in a new resolution number and have the resample checkbox turned off, all its doing is changing that dpi flag in the JPG file, which doesn't resample. I routinely do this very step in Photoshop and set my 20D images to 292 dpi. Why? Because it makes it an 8x12 image, which I find comforting to think in terms of. Why? No good reason whatsoever. But now when all my images are 8x12, and I go and grab a text tool, I know that a font of point size 12 will end up a certain size on the print, and that itself is rather convenient.

Dots per inch, pixels per inch, resolution, those are all terms that are confusing to most people, and usually doesn't matter. ALL THAT REALLY MATTERS IS HOW MANY PIXELS THE IMAGE ITSELF HAS. The "resolution" of that file is meaningless.

Mike Lane · May 25, 2005

mercphoto wrote:

Are you talking about Adobe Camera RAW, or Photoshop? ACR is CREATING the image from the RAW file. Thus its not a re-sample, its a first-creation.

From within Photoshop itself, if you go to Image Size and type in a new resolution number and have the resample checkbox turned off, all its doing is changing that dpi flag in the JPG file, which doesn't resample. I routinely do this very step in Photoshop and set my 20D images to 292 dpi. Why? Because it makes it an 8x12 image, which I find comforting to think in terms of. Why? No good reason whatsoever. But now when all my images are 8x12, and I go and grab a text tool, I know that a font of point size 12 will end up a certain size on the print, and that itself is rather convenient.

Dots per inch, pixels per inch, resolution, those are all terms that are confusing to most people, and usually doesn't matter. ALL THAT REALLY MATTERS IS HOW MANY PIXELS THE IMAGE ITSELF HAS. The "resolution" of that file is meaningless.

I only mean Adobe Camera Raw. I just looked into it and it appears that you can up or downsample your image in ACR but the default is to not do this. The 240ppi that it has as a default is almost entirely meaningless in terms of using smugmug. I think you answered my question.

mercphoto · May 25, 2005

Mike Lane wrote:

I only mean Adobe Camera Raw. I just looked into it and it appears that you can up or downsample your image in ACR but the default is to not do this. The 240ppi that it has as a default is almost entirely meaningless in terms of using smugmug. I think you answered my question.

Ah. Remember, though, that in ACR you have TWO settings that interest you most. One is the resolution setting, which you are referring to above. You can make that any value you want. Personally I do 292 dpi (for the 8x12" image size I mentioned earlier). BUT THIS HAS NOTHING TO DO WITH PIXEL COUNT. Once again, the resolution setting has nothing to do with up or down sampling.

There is another ACR list box that has to do with image size in terms of pixel count. One of the available choices will be the native pixel count of the RAW image. Another available choice will be twice as many pixels horizontal and vertical (meaning four times as many pixels overall). There is probably another choice or two as well.

So, the resolution setting in ACR does nothing whatsoever to the overall pixel count, meaning it does not up or down sample an image. It is a different setting in ACR that handles up or down sampling during conversion.

Baldy · May 25, 2005

When Marc Muench gave his talk at Yosemite, he showed utterly breathtaking shots which he prints large, and went on to say "they look great even at 100 dpi."

I honestly think resolution is a temptest in a teapot for continuous-tone photographic prints like EZ Prints makes. The only comments we hear about resolution are "stunning." Your mileage may vary with inkjets, which are not continuous-tone but dithered.

Just let EZ Prints do the resampling and concentrate on color, contrast, lightness/darkness and unsharp mask — the 4 factors that will be noticed (as opposed to the two that won't: dpi and jpeg compression level).

Mike Lane · May 25, 2005

Baldy wrote:

When Marc Muench gave his talk at Yosemite, he showed utterly breathtaking shots which he prints large, and went on to say "they look great even at 100 dpi."

I honestly think resolution is a temptest in a teapot for continuous-tone photographic prints like EZ Prints makes. The only comments we hear about resolution are "stunning." Your mileage may vary with inkjets, which are not continuous-tone but dithered.

Just let EZ Prints do the resampling and concentrate on color, contrast, lightness/darkness and unsharp mask — the 4 factors that will be noticed (as opposed to the two that won't: dpi and jpeg compression level).

It turns out that I hadn't been doing any resampling but I wasn't sure because the ppi thing threw me off. Now I know, and knowing is half the battle.

Yo Joe!

Resolution...yes this topic again...

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