Exposure in Previews inconsistant

[apisto]

I am a new user trying to get iMatch dialed in and I am having trouble with the previews for my Panasonic G9.  A small number of previews display many stops over exposed.  It only happens with a few images.  Typically the adjacent images in a series (with same exposure settings) are not affected.  Also, in other programs (Lightroom, DXO) these same files are displayed without the exposure problem.  Files from various Olympus, Pentax and Nikon cameras do not seem to be affected.

I tried a couple things without success:

-Tried installing a Fast picture CODEC pack, and forced iMatch to re-scan the database.
-Tried changing the "Prefer photools.com RAW processing and forcing a re-scan.

Hopefully I am neglecting something simple that will solve this.  Does anyone have any advice?  Thanks!

Also, I ran iMatch's WIC debug report after installing the codec pack:

WIC: Testing file 'G:\Photo\2020\06\P1029807.RW2'
   Thumbnail: Codec 'Panasonic Raw Decoder (FastPictureViewer Codec Pack)'
      (GetThumbnail failed (88982F44 The bitmap codec does not support a thumbnail.).) 0x0 pixel in 0 ms.
   Preview: Codec 'Panasonic Raw Decoder (FastPictureViewer Codec Pack)'
      (GetPreview failed (88982F81 The operation is unsupported.).) 0x0 pixel in 0 ms.
   Full resolution: Codec 'Panasonic Raw Decoder (FastPictureViewer Codec Pack)'
      () 1920x1440 pixel in 0 ms.


IMatch Integrated RAW Processing.

Analyzing image 'G:\Photo\2020\06\P1029807.RW2'
    Preview: (Format:1, Dimensions: 1920x1440) in 0ms. Result: 0
    Original Image: (5264x3904 5208x3904) in 3484ms. Result: 0

Version: 0.20.0-WorkInProgress
List of supported cameras: 1114
Adobe Digital Negative (DNG)
AgfaPhoto DC-833m
Alcatel 5035D
Apple iPad Pro
Apple iPhone SE
Apple iPhone 6s
Apple iPhone 6 plus
...
Panasonic DC-G9
...

[Mario]

IMatch by default uses the embedded preview in your RAW files, unless you disable this or the embedded preview is too small.

See: Working with RAW Images in the IMatch help for details, links and all related options.

The WIC codec installed on your system can only extract a 1920 pixel image from your RAW, but declares this as the full-size image:

Full resolution: Codec 'Panasonic Raw Decoder (FastPictureViewer Codec Pack)'
      () 1920x1440 pixel in 0 ms.

So IMatch will have to use that. IMatch first tries the preview (if enabled under Edit > Preferences > Cache).
If the RAW does not contain a preview, the preview is too small or the WIC codec cannot extract a preview (as in this case), IMatch uses the full RAW and lets the WIC codec develop it.
If neither the default Windows 10 WIC codecs nor the FPV codecs (which are no longer maintained) can handle the file, you have two options:

1. Uninstall the FPV codecs and install the latest set of Microsoft RAW codecs from https://www.microsoft.com/en-us/p/raw-image-extension/9nctdw2w1bh8?activetab=pivot:overviewtab
These are based on LibRaw and usually handle more format variants than the default WIC codecs in Windows.

2. Switch IMatch to use its own RAW processing based on LibRaw under Edit > Preferences > Application. Search for RAW on that page to find the Prefer photools.com RAW processing option.
According to the WIC diagnosis, LibRaw can extract the full RAW with 5264 x 3904 pixels.

Select the problem files afterwards in the File Window and press Shift+Ctrl+F5. Use the "Force Update" option so IMatch re-processes your files with whatever WIC codec is installed or LibRaw.

Does Panasonic not provide a WIC codec to their customers? I mean, Panasonic should know best about all their various RAW format variants and should be able to create a superior WIC codec which produces the best possible renditions. In all Windows applications which support the standard WIC technology, from Windows Explorer to IMatch to ...

[apisto]

Thank you for the tips.  I tried all you suggested, but the result has not changed, unfortunately.  I also searched on the web for a WIC Codec provided by Panasonic, to no avail.

[Mario]

This cannot be.

LibRaw can extract the full raw, as the WIC diagnosis log file you have provided shows.
When you switch IMatch to use LibRaw and then force an update, it will work.

Please upload a sample image somewhere and post a link. We can then check this out with one of your images.
I was joking about a WIC codec from Panasonic. They give a shit and don't provide one.

Note: When LibRaw or a WIC codec 'develops' your RAW, the result will be of course be different from the preview your camera produces or the results of your RAW processor. All use different settings and algorithms to convert the raw data into an image.


I have downloaded a number of sample RW2 files created with the G9 from a photography test web site.
Both images are processed fine by the Microsoft Raw Image Decoder WIC codecs for which I have provided a link above.

WIC: Testing file 'E:\data\__File Format Test Suite\Images\PANASONIC\G9\P1000131.RW2'
   Thumbnail: Codec 'Microsoft Raw Image Decoder'
      () 1024x768 pixel in 141 ms.
   Preview: Codec 'Microsoft Raw Image Decoder'
      () 1920x1440 pixel in 125 ms.
   Full resolution: Codec 'Microsoft Raw Image Decoder'
      () 5208x3904 pixel in 125 ms.

This indicates that the problem is on your computer.
Did you install the codecs as I explained? Removed the FPV codecs? Rebooted? Forced IMatch to reload the images with the new codecs?
I'm sure this will work for your PC if it works here for my development machine and a fresh Windows 10 installation (with only the Microsoft Raw Image Decoder update installed).

[apisto]

Thank you again for the assistance.

Yes, I have done as you directed. Removed FPV, installed MS WIC, rebooted and forced iMatch to reload/process.  But certain files are still showing way over exposed.

When you say switch iMatch to use LibRAW, you mean set imatch to "use photools.com RAW processing", correct?

Here is the log showing the MS WIC Codecs installed and also a preview is now being generated https://www.dropbox.com/s/71zbewqkstgc86y/IMatch_WICDiag_P1029807.txt?dl=0:

-------------------------------------------------------------------
WIC: Testing file 'G:\Photo\2020\06\P1029807.RW2'
   Thumbnail: Codec 'Microsoft Raw Image Decoder'
      () 1024x768 pixel in 188 ms.
   Preview: Codec 'Microsoft Raw Image Decoder'
      () 1920x1440 pixel in 219 ms.
   Full resolution: Codec 'Microsoft Raw Image Decoder'
      () 5208x3904 pixel in 188 ms.

WIC Result: A codec for this file format is installed and it looks like it fully supports the format.


IMatch Integrated RAW Processing.

Analyzing image 'G:\Photo\2020\06\P1029807.RW2'
    Preview: (Format:1, Dimensions: 1920x1440) in 16ms. Result: 0
    Original Image: (5264x3904 5208x3904) in 3453ms. Result: 0
-------------------------------------------------------------------
Sample RAW file that shows issue:  https://www.dropbox.com/s/9abtefw4fbms6c0/P1029807.RW2?dl=0

How iMatch exposes preview:
https://www.dropbox.com/s/ybn7dro9ze6vb5g/imatch.JPG?dl=0

How other image previewers expose preview:
https://www.dropbox.com/s/in5g1yz3l1wejgo/faststoneJPG.JPG?dl=0

[Mario]

The embedded preview in your images is only 1920.
Check the minimal cache size under Edit > Preferences > Cache.

If the minimal cache size configured there is larger than the small preview images in your images, IMatch falls back to "develop" the RAW data via the WIC codec (or LibRaw).
Whatever comes out of that will be used. Naturally, the results can be very different from what you see in your camera or RAW processor.

This is what I get from your sample RAW (WIC Codec: Microsoft RAW Image Decoder on clean Windows 10 computer).
The minimum cache size on my computer is 2,000 pixels so the embedded preview is not used.

When I lower the cache size to 1,000 pixels and force an update of the image, IMatch uses the embedded preview.
The differences to the "developed" RAW are minimal. I see no issues with this. See attachment below.

[apisto]

Thank you.

Per your recommendation, when I set the minimum cache size to 1920 the embedded, properly exposed, preview is used.  When set to 1921 or higher, the Microsoft RAW Image decoder leads to overexposed previews on a subset of the processed of images.

I will install iMatch on a second computer to try and duplicate your results, to try and narrow down what is causing this for me, since on occasion a full size preview is helpful when culling.

Thanks again.

[Mario]

A WIC codec is no RAW processor. I don't know which algorithms Microsoft or LibRaw apply. As I said, the outcome will be very different from what you get in a RAW processor.
IMatch is a DAM, not a RAW processor.

For consistent results, I recommend setting your camera to embed 100% previews.
Use your RAW processing software to produce a JPEG image with your favorite settings. Then make this a version in IMatch and set this version to be the visual proxy for the RAW. IMatch will then use the developed JPEG to represent the RAW. See Uses and Working with RAW Images