Newbie question: Jpeg output quality: 'Normal' vs 'Proof'

[auywy]

System: Linux Mint 64-bit

The official documentation states that when Image Size is set to 'Proof', the image is half-height and half-width of the original.

My question is what happens with the display of the image when I select 'Normal' size output, i.e. - 'Jpeg full size'. It looks very noisy. And I've checked multiple times to ensure that default rendering does not activate any image modifications or enhancements.

Here's what I did:
(1) Make adjustments to RAW file.
(2) Output to jpeg using 'Proof' quality - i.e. 'Jpeg Proof'. Quality: 90%.
(3) Use ASP file navigator to display the jpeg that was produced.
(4) Output the same file to jpeg using 'Normal' quality - i.e. 'Jpeg Full'. Quality: 90%.
(5) Use ASP file navigator to display the jpeg that was produced.

Proof screenshot: https://docs.google.com/open?id=0BxSfVO ... Q3MzUyMjgx

Full screenshot: https://docs.google.com/open?id=0BxSfVO ... A4NGM5YmNi

'Jpeg Full' displays higher noise. Is this normal? Some explanation for this? Not really critical since it's all used for web display anyway which should use a smaller size. But very curious about this.

[Ken Berry]

Please do not double post -- it only causes confusion. I have deleted your other post on the same subject.

[Gerard2]

If you view them in an other image viewer, does the same happen? when you view a jpg in ASP, the default sharpening / levels / contrast etc settings are aaplied. If you over sharpen something, its often noisy.

[tomsi42]

A down-scaled image will show less noise than a fullsize one.

Since the proof version is a downscaled version, I think this is what happens here too.

[afx]

The official documentation states that when Image Size is set to 'Proof', the image is half-height and half-width of the original.

Stay away from proof but define your own queue with defined sizes...

Resizing will reduce noise....
Check for noise in 100% view in AS before you generate output.

cheers
afx

[auywy]

Please do not double post -- it only causes confusion. I have deleted your other post on the same subject.

Noted. Apologies for the confusion.

[auywy]

If you view them in an other image viewer, does the same happen? when you view a jpg in ASP, the default sharpening / levels / contrast etc settings are aaplied. If you over sharpen something, its often noisy.

I get strange results when I try using different applications.

When the image is viewed in the default Gnome image viewer (EOG), it looks noisy.

When the same image is viewed in gThumb, Gimp or Shotwell, it looks smooth.

I should mention that I've been shooting RAW+JPEG. ASP displays straight-from-camera JPEGs perfectly fine. It's only the Jpegs that I output from RAW in ASP that exhibit this strange behaviour. As mentioned, the same image that I output from RAW with 'Full' quality renders smooth in gThumb, Gimp and Shotwell, but noisy in EOG and ASP. Something different about the way these applications render Jpeg? Some geeky googling turns out a few threads talking about libjpeg in Linux and how some applications still rely on an old version. Related?

I should also clarify I view everything via the file navigator, and my default (jpeg) rendering options have 'sharpen' unchecked.

And thanks for the replies so far.

[afx]

EOG is junk, it does not understand CM, so I suggest not using it.
But having said that, this is not the issue here. When images are displayed downsampled, the method used for this will have to be taken into account. Every app uses different methods. EOG and AS are both not brilliant in that regard. Taht can amplify noise.
So again, make sure you compare at 100%...

cheers
afx

[grubernd]

The official documentation states that when Image Size is set to 'Proof', the image is half-height and half-width of the original.

Stay away from proof but define your own queue with defined sizes...

in short: "Proof" is optimized for speed and dumps quality for that.

it is your choice if you need halfway decent images and you need them fast.
that would be for selection by someone else, contact sheets or anything else
where the general appearance of the image is more important than pixel-level quality.

[auywy]

Thanks to all who replied. I'm switching to using other photo organizer utility to organize the jpegs, and using ASP only for RAW image processing.