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Author Topic: Size of JPG output by C1  (Read 5399 times)
jeremyrh
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« on: July 03, 2011, 11:26:29 AM »
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I know this makes no sense, but it seems that C1 produces very large JPG files - much bigger than PS or Aperture - for "medium" levels of quality. Does C1 have a different definition of "medium" (quality = 50, for example) or is there some other information being included in the file that makes it bigger?

Thanks for any enlightenment!!
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Jack Flesher
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« Reply #1 on: July 03, 2011, 03:53:54 PM »
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Click on the "advanced" tab and you can set all your jpeg output parameters.
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jeremyrh
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« Reply #2 on: July 04, 2011, 01:44:57 AM »
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Click on the "advanced" tab and you can set all your jpeg output parameters.
Thanks - I do that, and click everything "off" but the file is still big, hence my question about whether there is something included that I can't avoid, that pumps up the size.

I guess I could make some experiments to see if a given file size in C1 looks the same at the same size exported from PS ...
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BartvanderWolf
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« Reply #3 on: July 04, 2011, 08:15:23 AM »
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Thanks - I do that, and click everything "off" but the file is still big, hence my question about whether there is something included that I can't avoid, that pumps up the size.

I guess I could make some experiments to see if a given file size in C1 looks the same at the same size exported from PS ...

Hi Jeremy,

It's not only the amount of compression, but also the amount of chroma sub-sampling that changes in Photoshop. Perhaps C1 always uses a better quality sub-sampling, even when compression is set to high (overall quality is lower)?

I haven't tested the C1 JPEG quality, but that is where you can focus your attention to spot the differences. You'll notice the increased loss of fine color detail when the compression increases. You can e.g. use this image from Roger N. Clark to test (convert from indexed to RGB mode first, and save as a TIFF for use with C1). The compression/subsampling artifacts look different at different brightness levels, so you could make a brighter and darker version as well. There can also be a difference between the accuracy of horizontal and vertical features.

You can also use the image used on this page, and count the number of remaining colors.

Cheers,
Bart


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Doug Peterson
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« Reply #4 on: July 04, 2011, 05:31:01 PM »
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They all have different and proprietary definitions of "medium" quality (and all the other numbers on the scale). None of them are more "right" than the others (they are all arbitrary scales) so it wouldn't be accurate to say "pumps up" the file size. But yes, generally speaking a lower number will be required in C1 to match a medium number in Photoshop.

Quick test won't take you more than 10 minutes to determine what number you want to use.

Doug Peterson (e-mail Me)
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jeremyrh
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« Reply #5 on: July 05, 2011, 03:29:14 AM »
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They all have different and proprietary definitions of "medium" quality (and all the other numbers on the scale). None of them are more "right" than the others (they are all arbitrary scales) so it wouldn't be accurate to say "pumps up" the file size. But yes, generally speaking a lower number will be required in C1 to match a medium number in Photoshop.

Quick test won't take you more than 10 minutes to determine what number you want to use.


Doug -Thanks for your reply. Of course I'm aware that the numbers on the scale are arbitrary, like the numbers on the dial of my stereo, but my question was about if there is some extra information - a preview, or thumbnail image for example - that is included in the C1 file and increases its size in a way that does not add to the main image. Maybe that question just underlines my ignorance about the jpeg format, but anyway, I'm understanding that the answer is "no".
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mediumcool
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« Reply #6 on: July 31, 2011, 05:59:36 AM »
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I donít have PS on my main computer (donít ask!) so I export images from C1 as TIFFs and set Preview to open them.

Then I save them out as JPEGs with a bit of slider-sliding. Must check the results against PS one day.
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lkuhlmann
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« Reply #7 on: September 07, 2011, 09:12:12 AM »
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Hi.

I find your question very relevant. We have actually provided a "guide" to get the best jpg quality vs size from Capture One, take a look at this blog:
http://blog.phaseone.com/2010/12/

-Lionel
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