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Author Topic: Upsizing: Lightroom vs. ACR (vs. DPP)  (Read 8574 times)
tgphoto
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« on: June 19, 2006, 09:08:41 PM »
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Hello,

I have now spent the weekend testing Lightroom Beta 3, and have come across something interesting in how Lightroom handles upsizing of images. If I choose to export an image from Lightroom (File > Export), I can enter ANY dimension for width or height, as well as ANY resolution. This is a level of customization I have never seen before in an imaging software.

Similarly, if I edit the same image in Adobe Camera Raw, under Workflow Options, the dimensions are limited by the type of file (I am guessing its total megapixel count). For example, my Canon 10D files can only be upsized to 4096x6144 (25.2 MP), which at optimum resolution (360) results in a file roughly 11"x17".

What I'd like to know is, is it better to upzise an image using Lightroom or Adobe Camera Raw, and, in the case of Lightroom, is there any drawback to setting the output size to something largerthan is normally possible with Adobe Camera Raw?

Thanks!

Tim

(Sidenote: While experimenting this weekend with Lightroom and ACR, I threw in Canon's DPP software for kicks. Turns out, Canon too sets an "upper limit" on upsizing. However, I can easily upsize to 16"x24" at 360 using DPP, which is a significant gain over Adobe Camera Raw)
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tgphoto
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« Reply #1 on: June 20, 2006, 02:07:59 PM »
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So...54 views but nobody has an opinion on this?  C'mon, Michael, help me out here!  Did I ask something extremely foolish?
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bob mccarthy
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« Reply #2 on: June 20, 2006, 02:28:10 PM »
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The output for ACR is only relative to the viewing size in photoshop, not final print size. You can go into PS after processing in ACR and resize  to whatever DPI you want. For final print you can up(down)res it to any output size you want (using bicubic or equivalent) and resize to other than native output.

Lightroom is a program that works from raw to print -  one program.

ACR + Photoshop is a two step approach to print.

Bob
« Last Edit: June 20, 2006, 02:31:44 PM by bob mccarthy » Logged
tgphoto
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« Reply #3 on: June 20, 2006, 02:45:53 PM »
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Bob,

I appreciate the reply.  Yes, I realize I can use Photoshop to then increase the print dimensions further, but this comes at a loss of resolution.  What I am getting at is this...

ACR places a limit on how much you can upsize a file, which is directly related to the original file's megapixel count.  Lightroom does not have this limitation, as you can export a file upsizing it to any dimension at any resolution you choose.

So if I can take the same file I upsized in ACR and upsize it further in Lightroom, great!  But if all I am doing is pushing the file beyond its means, that file will fall apart and the resulting print will be of poor quality.
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bob mccarthy
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« Reply #4 on: June 20, 2006, 03:21:46 PM »
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Bob,

I appreciate the reply.  Yes, I realize I can use Photoshop to then increase the print dimensions further, but this comes at a loss of resolution.  What I am getting at is this...

Not at all. Its just a number. When you allow upsizing in PS, only then does bicubic come in for better or worse. If you select 300 dpi in acr it just gives this to Photoshop to cvalculate the size of the image on the computer screen. The data is not touched otherwise.



ACR places a limit on how much you can upsize a file, which is directly related to the original file's megapixel count.  Lightroom does not have this limitation, as you can export a file upsizing it to any dimension at any resolution you choose.


Don't worry about ACR. Final output size is set in Photoshop not ACR. You can set the DPI anything you want to in ACR without impacting the final file size.
The file size is finite,  but the output size can be darn near anything within reason by invoking bicubic (sharpner/smoother) in Photoshop.. You might want to look at how the print size is selected in Photoshop. It can be bound to file size or unbound and resized based upon bicubic


So if I can take the same file I upsized in ACR and upsize it further in Lightroom, great!  But if all I am doing is pushing the file beyond its means, that file will fall apart and the resulting print will be of poor quality.
[a href=\"index.php?act=findpost&pid=68670\"][{POST_SNAPBACK}][/a]

One can always overdo it when uprezzing the output.


Bob
« Last Edit: June 20, 2006, 03:25:54 PM by bob mccarthy » Logged
Schewe
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« Reply #5 on: June 20, 2006, 04:13:59 PM »
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What I'd like to know is, is it better to upzise an image using Lightroom or Adobe Camera Raw, and, in the case of Lightroom, is there any drawback to setting the output size to something largerthan is normally possible with Adobe Camera Raw?

Since Beta 3, Lightroom and Camera Raw share the same raw processing pipline. Both at hard limited to a max of 10,000 pixels in any deimension, but both Lightroom and Camera Raw are using the same uprezing.
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jani
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« Reply #6 on: June 21, 2006, 07:03:58 AM »
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So if I can take the same file I upsized in ACR and upsize it further in Lightroom, great!  But if all I am doing is pushing the file beyond its means, that file will fall apart and the resulting print will be of poor quality.
It doesn't matter which program you use; the image won't magically grow extra detail.

Any kind of upsizing of the image in terms of number of pixels means that you're "pushing the file beyond its means".

There are technical uses for upsizing an image which may lead to better image quality in larger prints, of course, but the fundamental problem is the same.
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« Reply #7 on: June 22, 2006, 05:32:16 PM »
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ACR does indeed have unlimited upressing, just like Lightroom. (The preset sizes are just for convenience, although I find that if I use the setting for exactly double the file size I get the best upressing.)

Under the Crop tool sub-menu there is a custom crop option where you can set any size, including any larger size. Set this and then 'crop' the image and the new size will be applied.

I have not tested for quality 'rigorously' but it seems that it is no better or worse than upressing afterwards in PS, it just saves time.
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Nick Rains
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« Reply #8 on: June 23, 2006, 08:41:21 AM »
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I have not tested for quality 'rigorously' but it seems that it is no better or worse than upressing afterwards in PS, it just saves time.
[a href=\"index.php?act=findpost&pid=68920\"][{POST_SNAPBACK}][/a]

That's my experience too. In theory, doing this on a linear encoded file should be "better" but in reality, I hardly see any difference. The differences are so subtle you need to subtract the two files and view the results in a new doc (use Calculations). There are differences at the pixel level but not a lot,

If you know up front you need to upsize the rendering, do it in the converter. If not sure, don't and wait until later.
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Andrew Rodney
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tgphoto
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« Reply #9 on: June 23, 2006, 08:49:05 AM »
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Thanks guys for the advice!  I did some testing yesterday and it looked like in some cases, doing it in converter worked better; other times, not as good.
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