Color Shift On Preview, Raw Size Change To Half

[Katamara]

Hello.

Regarding: XnViewMP 0.81

I've noticed a color shift when changing;
Tools > Settings > View > Camera RAW, use "Half Size"

Example 1: 'Camera RAW, use Embedded Preview'
Correct Preview Displayed.

Correct Preview

Selection_002.png (153.95 KiB) Viewed 2889 times

Example 2: 'Camera RAW, use Half size'
Incorrect Color Shift.

Incorrect Preview

Selection_004.png (215.67 KiB) Viewed 2889 times

Example 3: Settings, Embedded Preview

Settings Correct

Selection_005.png (31.58 KiB) Viewed 2889 times

Example 4: Settings, Half size

Settings, Half size

Selection_003.png (31.21 KiB) Viewed 2889 times

Questions;
1. Is my obervation correct, the 'Half size' is processing the entire RAW file to achieve a 1/2 sized preview ?
2. What would this be used for, since the color is incorrect ?
3. Is a 'Half size' embeded preview available, it hopefully would display faster ?

Thank you much.

[XnTriq]

What are your settings for the following options?

• File (view mode) » Format settings... » Read » Camera RAW
• Tools » Settings... » General » ICC

1. Is my obervation correct, the 'Half size' is processing the entire RAW file to achieve a 1/2 sized preview ?

RAW function is based on dcraw from Dave Coffin - http://www.cybercom.net/~dcoffin/dcraw/

Code: Select all

-h     Half-size the output image.  Instead of interpolating, reduce each 2x2 block of sensors to one pixel.  Much faster than -q.

The -h option of DCRAW selects the half-size output image. With this option, the most recent version of DCRAW (v8.77) averages the two green pixel values—earlier versions discarded one green pixel value.

• Wikipedia
  • Raw image format » Processing
  • Demosaicing

[Katamara]

Settings 1: View Mode > File > Format Settings

Settings: View > File > Format Settings

Selection_001.png (14.57 KiB) Viewed 2862 times

Settings 2: Tools > Settings > General > ICC = [All Off]

I'm lost in planet settings.

1. When in Browser/View modes, I'm seeing a slight color shift when clicking on the jpeg
original and the RAW. Since XnViewMP is in theory displaying the
'Preview jpeg image' inside the RAW, shouldn't the RAW and JPG originals display the same ?

2. Would you please recommend the correct settings in XnViewMP for displaying identical
original Jpeg and related RAW (preview jpeg) ?
e.g. DSC00223.JPG , DSC00223.ARW

3. What is the 'Half Size' dcraw function supposed to be used for ?

Thank you again.

[XnTriq]

1. When in Browser/View modes, I'm seeing a slight color shift when clicking on the jpeg original and the RAW. Since XnViewMP is in theory displaying the 'Preview jpeg image' inside the RAW, shouldn't the RAW and JPG originals display the same ?

Not necessarily

Note that in neither case will your work on the raw file or on the JPEG (rating, flagging, keywording, developing, etc) transfer to the other. Particularly in the case of Develop work, I would argue that you would not want it to — your raw file and JPEG will look different out of the camera — the same Develop decisions will often not be appropriate. If you have imported both the raw file and JPEG and want to work on them together, you can use Sync or Auto Sync to do so.

What Is Raw?

Raw is an image format which remains uncompressed and contains unprocessed or undeveloped data from the image sensor. It’s called ‘Raw’ because the data is untouched by the camera. Shooting in this format allows for the maximum image quality and detail to be obtained.

Because Raw files are unprocessed, they come out of the camera looking flat, low in contrast and a little dark. Before they can be printed or displayed they need to be processed in a program like Adobe Lightroom or Photoshop.

What Is JPEG?

A JPEG file is processed and compressed by the camera (according to the manufacturer algorithms) before it is written to the memory card.  JPEGs are processed within the camera and are immediately ready to print or share.

dpBestflow.org explains it like this, “The essential feature of JPEG capture is that the camera shoots a Raw file and applies camera settings, such as white balance, sharpening, contrast, and saturation… the Raw file is then processed out to a JPEG and the original Raw data is deleted.” Because of this, JPEG images usually look great straight out of the camera versus Raw images which look dull and lifeless.

They key difference here is that JPEG images have been processed and compressed and some of the original data is discarded. Sadly, you’ll never get that original data back. Whereas a Raw image is exactly how the camera’s sensor saw it, without any extra information added like brightness, color and sharpness, and without any compression or data being discarded.

Perhaps you must know that the 'preview' is a 'doctored' image of the actual RAW data. Let me say it again: When you look at the embedded preview you look at other image than the actual RAW image. Usually some curves, increased contrast, saturation, sharpen etc. are applied.

See bellow the difference between the thumb in top-left and the actual raw data (bottom) of the same file of a high-quality digital back (Hasselblad H4D). The purpose of the raw file isn't to look 'pretty' but to keep as much information as possible. That's why, generally, in order to keep as much as they can from the dynamic range of the light which hits the sensor, the colors appear dull, lacking contrast (especially if the files use Adobe RGB color space). If you do some PP the image will look indeed prettier, but this isn't the purpose of the RAW data.



There are brands/cameras known to do enough PP before saving the thumb in the Raw file. Perhaps that's why Photoshop's Camera Raw plugin has a special tab (page) dedicated to presets for each camera model they support which mimic the PP applied by the camera on the Raw data. Hence if a beginner wants to see his Raw "exactly like he saw it in Explorer", he can go on that tab and choose "Normal", "Vivid" etc.

[XnTriq]

2. Would you please recommend the correct settings in XnViewMP for displaying identical original Jpeg and related RAW (preview jpeg) ?
e.g. DSC00223.JPG , DSC00223.ARW

I wish i could give you a definitive answer, but I'm afraid that there's no way to make MP display raw sensor data and embedded JPEG preview exacly the same.

Unpredictability when working with rendered file types

Now that parametric image editing is available for rendered file types like JPEF, TIFF, and PSD, there are some new drawbacks. It’s generally well known that the look of a raw file is dependent on PIEware settings, but most people expect rendered files to look the same from program to program. This expectation can lead to unpredictable rendering of images.

For instance, if you adjust a JPEG file with Lightroom, the image will be displayed inside the Lightroom application with the adjustments applied. If you view this same file with a program that does not understand the rendering instructions, the image will look like it did before the settings were applied, creating confusion, or worse. If you send the image off for expensive reproduction with the assumption that it will show the adjustments, and instead it comes back with the original version showing, someone might suffer a financial loss. If you work with rendered files parametrically, be careful about what images get sent out.

A “pretty good print”

The DNG file can store not only the “negative,” but also a “print.” You can create an embedded preview that reflects all the adjustments you have made. You can correct the color, brightness, and contrast — even crop or apply a curve — and then store the resulting image inside the DNG file. This embedded preview can be of several sizes, including one that is the full dimension of the RAW file.

Private maker notes

If a camera manufacturer comes up with a new way to process a file and wishes to keep the details secret, it can encrypt this information into the DNG file. Thus, DNG files can be universally accessible, while at the same time offering manufacturers protection for their proprietary image-processing algorithms. This will be useful as more manufacturers let users choose DNG as a raw file format to be produced straight out of the camera, or as a processed output from their software.

I just checked my camera settings and they are on sRGB (whatever that exactly means) and JPEGs from this camera are shown correct by XnView.

Strangely enough, I missed that part on my first reading...

You can set sRGB or AdobeRGB with a digital camera and that setting will apply to JPEGs. For RAW files (like your NEF), colors are not stored in sRGB (nor in AdobeRGB) but in reference to the camera profile.

I don't know how XnView handle this. In particular: I am not sure that the camera color profile is actually available in the file, as it could be technically possible for Nikon to manage this in its RAW converter only...
(it would also mean that XnView would need color profiles for all cameras in such situation)

[XnTriq]

3. What is the 'Half Size' dcraw function supposed to be used for ?

Choosing Half size as the format setting for reading Camera RAW will speed up generating thumbnails, display in browser preview and the viewer, as well as batch processsing.

[Katamara]

Thank you for your answers.
I don't think I articulated enough.

I've extracted the 'preview' or jpeg image embedded in the RAW file.
I understand the processing of RAW/jpeg.
I have not made any changes to the original RAW file.

What I don't understand is, since XnView is displaying the embedded jpeg
when the RAW file is clicked, I'm anticipating identical display when clicking
on the extracted jpeg derived from the RAW file. Hopefully, I've made the
correct settings choices.

I am noticing a slight difference in displayed color from the extracted jpeg,
and the unaltered corresponding RAW file (embedded jpeg).

Thanks again for your fantastic support.

[XnTriq]

As it turns out, the format of the previews embedded in my test DNGs is actually TIFF. Could you please tell me your camera model or send me a sample file?

A word of caution: I'm by no means an expert on working with RAW files. I don't own Lightroom, and my version of Photoshop is older than I care to admit. Any advice from a more experienced forum member would be greatly appreciated.

[Katamara]

Thank you anyway.

I'm a little at my end and will have to live with the differences.
There is a slight color shift towards green, so be it.

I am completely calibrated all the way through and hyper-observant.

Apparently, an image displayed when the 'Raw' image is clicked, and the image
displayed when the extracted Raw jpeg is clicked are 'supposed' to be identical ?
Yes ?

By the way, Lightroom isn't required to extract a jpeg embedded in a RAW file.

By the way 2... Does anyone else have any opinions on this issue ?

Best regards.

[XnTriq]

The windows versions of ERawP and Exiv2 were used to extract the embedded previews of various RAW flavors downloaded from rawsamples.ch. The resulting JPEGs/TIFFs were bit-for-bit identical and did not contain any metadata or color profiles.

Athough I systematically tried all combinations possible in Format settings..., MP v0.81 didn't produce the same output for RAW files and their corresponding extracted previews.

[Katamara]

Sounds like the same color shift anomaly I've been experiencing.
It is my hope that it will get addressed at some point.

Thank you for your assistance.

Cheers.

[XnTriq]

PS (in-camera RAW processing):

If you shoot RAW files you’ll have noticed by now that the colours and tonal renditions you get from third-party RAW converters like Adobe Camera Raw, DxO Optics Pro or Capture One do not quite match those of the in-camera JPEGs.

That’s because the camera has its own internal RAW converter. Whether you shoot RAW or JPEG, the image is initially captured as RAW data. If you shoot RAW, the RAW files are saved out as-is to the memory card. If you shoot JPEGs, the RAW data is converted on the fly into JPEGs, which are then saved on the card.

The thing is that all RAW converters are different. Third-party RAW converters don’t use the same RAW conversion process as the camera (or the camera maker’s own RAW conversion software). Instead, they use their own. It’s like swapping from a film maker’s own developer in the old days, to a different formulation from an independent company.

[Mixer]

Why does dcraw output have a green tint and weak color?

• Because dcraw doesn't have a color matrix for your camera model, it outputs raw color instead of sRGB. To fix this, I need a photo of a Wolf Faust, ColorChecker, CMP, or other calibrated color chart. Follow this checklist:
  • Use a real chart, not a printout or screen image.
    Wait for sunny weather, local noon ± two hours.
    Carefully brush any dust off the chart.
    Tilt the chart 90° to the camera and 45° to the sun to avoid specular reflections.
    Set the camera two meters away and use telephoto zoom.
    Use the lowest ISO setting.

Try viewing with this http://arwviewer.com/