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Option to set the quality of JPG in percent

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Option to set the quality of JPG in percent
« on: 10 / April / 2008, 15:33:14 »
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The "superfine", "fine", "normal", are for the normal users and they don't tell so much...

It would be usefull to be able to set 100% quality or 1%... if needed.
What about encoding JPEG 2000 which has higher bit depth? Is it possible to do it?

What is the camera quality [%] at "superfine" mode?

Re: Option to set the quality of JPG in percent
« Reply #1 on: 10 / April / 2008, 16:05:16 »
What is the camera quality [%] at "superfine" mode?

"superfine" is about 98% jpeg quality.
"fine" is about 94%.
"normal" is simply horrible.

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Offline GrAnd

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Re: Option to set the quality of JPG in percent
« Reply #2 on: 10 / April / 2008, 16:49:23 »
"superfine" is about 98% jpeg quality.
"fine" is about 94%.

I suspect there should be more than 4% difference between these two modes...
"superfine" is more likely 85-90%
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Re: Option to set the quality of JPG in percent
« Reply #3 on: 10 / April / 2008, 17:18:15 »
Than there -must- be a hack to be able to save 100% quality JPG! :)

It will allow us to shoot the best JPG's strait into the camara memory, with no need for converting between RAW --> JPG for pictures/scenes that do not require RAW shooting.

98% is not enough!
The file size is heavily compressed between 100%-90% quality settings.


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Offline GrAnd

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Re: Option to set the quality of JPG in percent
« Reply #4 on: 10 / April / 2008, 17:29:09 »
The file size is heavily compressed between 100%-90% quality settings.

I took a JPG file from A610. It was 2MB. Then I opened it in Photoshop and tried to export it with several quality settings. I've got the similar size on 85%. And I've got 3MB file if I set the quality to 100%.
CHDK Developer.

Re: Option to set the quality of JPG in percent
« Reply #5 on: 10 / April / 2008, 18:27:50 »
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« Last Edit: 22 / April / 2008, 17:17:37 by Barney Fife »
[acseven/admin commented out: please refrain from more direct offensive language to any user. FW complaints to me] I felt it imperative to withdraw my TOTAL participation. Nobody has my permission, nor the right, to reinstate MY posts. Make-do with my quoted text in others' replies only. Bye

Re: Option to set the quality of JPG in percent
« Reply #6 on: 10 / April / 2008, 23:04:48 »
JPEGsnoop gives a lot of information on the quality of JPEGS. You may like to check this utility.

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Offline gabriele

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Re: Option to set the quality of JPG in percent
« Reply #7 on: 14 / April / 2008, 06:54:23 »
Sorry for the lenght of the post, but this is the output I got with JPEGsnoop from a picture taken with my A630 with superfine quality:

  Precision=8 bits
  Destination ID=0 (Luminance)
    DQT, Row #0:   1   1   1   1   1   2   3   3
    DQT, Row #1:   1   1   1   1   1   3   3   3
    DQT, Row #2:   1   1   1   1   2   3   3   3
    DQT, Row #3:   1   1   1   1   2   4   4   3
    DQT, Row #4:   1   1   3   4   4   6   6   4
    DQT, Row #5:   1   2   3   3   4   5   6   5
    DQT, Row #6:   2   3   4   4   5   6   6   5
    DQT, Row #7:   5   5   5   5   5   5   5   5
    Approx quality factor = 97.24 (scaling=5.52 variance=1.65)
  ----
  Precision=8 bits
  Destination ID=1 (Chrominance)
    DQT, Row #0:   1   1   2   4   6  11  11  11
    DQT, Row #1:   1   1   2   4   8  11  11  11
    DQT, Row #2:   2   2   3   4  11  11  11  11
    DQT, Row #3:   4   4   4   5  11  11  11  11
    DQT, Row #4:   6   8  11  11  11  11  11  11
    DQT, Row #5:  11  11  11  11  11  11  11  11
    DQT, Row #6:  11  11  11  11  11  11  11  11
    DQT, Row #7:  11  11  11  11  11  11  11  11
    Approx quality factor = 95.17 (scaling=9.67 variance=5.29)


Re: Option to set the quality of JPG in percent
« Reply #8 on: 14 / April / 2008, 10:50:49 »
There's some little utility out there somewhere in net-land, that allows you to run it on any JPG file and it's supposed to tell you the compression sub-sampling used as well as an estimated percentage of the compression. I don't recall the name of the program or where to find it. But if any of you find that you could use it to get more exacting results of what's really being used.





jpgQ -JPEG Quality Estimator is a kind of such utility. you might want to check this out: jpgQ Estimator

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Offline jetzt

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Re: Option to set the quality of JPG in percent
« Reply #9 on: 14 / April / 2008, 11:10:03 »
Quote
jpgQ -JPEG Quality Estimator is a kind of such utility. you might want to check this out: jpgQ Estimator
Why not you, if I'm allowed to ask? :P

 

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