Monochrome2DNG - File Converter for «Monochrome-Converted» Cameras

Application for color cameras converted to Black and White.

Almost all digital cameras that are released today are color cameras. Several Leica and PhaseOne models are rare exceptions, but these cameras are even more of a niche product than the color cameras or digital backs made by those same companies. Nevertheless, there is demand for BW (Black and White) cameras (for reasons explained in detail below), and many photographers want BW cameras with the same lens mount as their main (color) camera, so that they can use the lenses they already own.

Since a color camera differs from a BW camera due to the existence of color filter array (CFA, Bayer mosaics) over the sensor, converting a color camera to BW is done by removing the CFA*.

After the CFA is removed, the demosaicking process that is done during RAW file processing becomes unnecessary. This, in turn, leads to higher resolution and a decrease in the number of processing artefacts (see the Bayer Moiré article), which is, essentially, why people perform the conversions of color cameras to monochrome.

Monochrome2DNG Beta 0.9

However, during such conversion, the firmware of the camera doesn’t change, and the camera doesn’t know that it’s become monochrome, which leads to the following:

  1. The monochrome file recorded by the camera cannot be told apart from a color shot without a complete analysis of of the RAW data – all of the metadata corresponds to the color file.
  2. In many cameras, sensor data is processed differently for different color channels before the RAW is recorded (for example, White Balance preconditioning for Nikon: the values of the red and blue pixels are multiplied by small coefficient). In the case of a camera converted to monochrome, equally exposed pixels that originally, before conversion, belonged to different channels, receive different RAW data numbers.

The first problem leads to most RAW processing programs continuing to think that they’re processing a color file and, accordingly, preform demosaicking, which leads to resolution decreases, moiré, and aliasing.

The image below shows the same shot taken with a Canon 6D (converted to a monochrome camera) and processed by Adobe Camera RAW 10.2. On the left, it’s been processing like a color file (ACR will do this “by default”). On the right, the same RAW data, but ACR has read it as monochrome.

ACR conversion vs  Monochrom2DNG conversion. Resolution Moire

If you shoot any longish patterned object, the aliasing and moiré can occur on an even greater scale. Here’s a shot of a computer monitor, scaled to 50%, on the left is “processed as color” and on the right is “as BW”:

RAW processed as color vs processed as BW - the aliasing and moiré

The second problem, different in-camera processing of “different color channels”, manifests as a grid-like pattern on even surfaces (visible only with high zoom: the size of the element is 1 pixel):

In-camera processing vs Monochrom2DNG conversion

Various programs, including RawPhotoProcessor, AccuRaw Monochrome, and darktable support processing “without demosaicking” (not all of the listed programs can automatically suppress mosaic artifacts), however it’s impossible to use more popular RAW converters (Adobe Lightroom/Camera RAW, Capture One, DxO, etc.) normally with files that have been recorded by cameras converted to monochrome: the above-described problems will appear.


Monochrome2DNG (Beta 0.9)

The Monochrome2DNG utility is intended to make using cameras converted to monochrome easier:

  • It takes input files from cameras that have been converted to monochrome.
  • It then saves it as “truly” monochrome DNG files, suitable for using with popular converters that support the DNG format (that is to say, almost all of them).
  • With this:
  • One can turn on automatic “monochrome” recognition and convert only the files from converted cameras (so one can process a large archive that has both color and monochrome files in it quickly, in one pass).
  • Automatic mosaic pattern suppression is supported (output files will not have 1-pixel grid patterns)
  • Several formats for output DNG are supported, which allows one to use their RAW converter optimally.
  • Filter input files by Vendor/Model/Camera serial to process large archives faster.
Monochrome2DNG. Main Screen

Supported Cameras

Monochrome2DNG doesn’t have any specific settings for separate cameras. All cameras with Bayer or X-Trans sensors that are supported by the LibRaw library should be supported.

System Requirements

  • OS and CPU
  • Windows *: Windows 7 – Windows 10, 64-bit
  • Mac OX: Mac OS X/macOS 10.6-10.13, 64-bit processor (so, all Intel Macs, except for some models from 2005-06 with Core Solo and Core Duo processors)
  • Screen resolution no less than 1600x900
  • 50MB of disk space for the application

Download Links

Changelog

v0.8.1: Preferences - Override black level added.

v0.8.2: DefaultCrop* tags are written in DNG even if crop margins are not set.

v0.8.3: Fixed font size auto-selection on 1st run.

v0.8.4: Better handling of file names in non-default system locale/language.

v0.8.5: Just version update to extend beta expiration time to Sept 1, 2018

v0.8.6: Panasonic RW2 files: add LensName and LensSerialNumber to EXIF data

v0.9.0: Implemented mosaic suppression for non-uniform grid patterns (use Preferences - Mosaic Suppression - Method B to enable new method)

v0.9.1: Panasonic RW2 bad pixels filtering; camera model change settings.

v0.9.2: Preferences-Crop Mode: 'hard crop mode' implemented.

Changelog in more details

Getting in touch with us

This is a beta version, and it’s important to us to know your thoughts and suggestions. To contact us, please use:

... and a little bit more about CFA removal

* Because a color camera differs from a BW camera due to the presence of a color filter array (CFA, Bayer mosaics) over the sensor, converting a color camera to BW looks (theoretically) simple. Just remove the CFA, and your monochrome camera is ready. Of course, it’s not as simple as it sounds, especially on DSLRs (because of possible AF issues): not only is removing the CFA a difficult task, when removing CFA you will have to disassemble the sensor sandwich (cover glass removal is not trivial on some cameras), remove the CFA and micro-lenses from the top of the sensor (taking care not to damage the sensor itself), re-assemble the sandwich, and perform alignment, “but those are just details.”

Such conversion is done both by specialized companies (Llewellyn Data Processing (LDP) LLC, Cooled DSLR, Monochrome Imaging Services, HyperCams and Mods, and by individual enthusiasts.

Comments

Just tried it on my A7rII(m) (from monochromeimaging). The output is 8 bit files. This is a difference compared to the other RAW converters (for example Dark Table) listed in the article.

Dear Sir:

We never saw 8-bit raw files from Sony. The raw files we saw are 14-bit for uncompressed, and effectively 13 bit for compressed. How did you determine the files are 8-bit? Could you please upload a raw ARW sample and a converted DNG and send us the links to mono2dng-feedback@libraw.com

Thanks for setting me right. Changing the export settings in PS resulted in the correct output.

Dear Sir:

Thank you for letting us know it works for you.

Which menu and preferences did you use to get the highest resolution DNG file from the RAW file. 

"In many cameras, sensor data is processed differently for different color channels before the RAW is recorded (for example, White Balance preconditioning for Nikon: the values of the red and blue pixels are multiplied by small coefficient). In the case of a camera converted to monochrome, equally exposed pixels that originally, before conversion, belonged to different channels, receive different RAW data numbers."

"different in-camera processing of “different color channels”, manifests as a grid-like pattern on even surfaces (visible only with high zoom: the size of the element is 1 pixel)"
On a monochrome converted Nikon, does the pre-conditioning of RAW data consist only of applying R and B WB multipliers....if so could this be avoided by using a UniWB during capture. Similarly on an 830IR converted Nikon (in which the R, G and B Bayer filters have very similar but not exactly the same absorption response), could the mosaic resulting from pre-conditioning be somewhat avoided by using a scene referred WB?

Dear Sir:

does the pre-conditioning of RAW data consist only of applying R and B WB multipliers

You can determine if adjustments in digital domain are applied to channels looking at the histogram in rawDigger in Linear X-Axis / Bin:1 mode. If the histogram has gaps, raw data was digitally manipulated before recording. Strong combing in the histogram may also indicate digital adjustments.

could this be avoided by using a UniWB during capture?

No.

could the mosaic resulting from pre-conditioning be somewhat avoided by using a scene referred WB?

Likely, no.

> could this be avoided by using a UniWB during capture? No.
> could the mosaic resulting from pre-conditioning be somewhat avoided by using a scene referred WB? Likely, no.
If you can spare the time I would appreciate understanding why.....what else does pre-conditioning in some Nikon cameras apply other than a WB correction that would effect the creation of the mosaic grid.

Dear Sir:

Pre-conditioning is not WB correction, it is sensor colour calibration.

Sorry that was a dumb (disracted) moment idea on my part and I do know better....of course it is not a WB correction otherwise it would not be possible to easily switch WB post RAW capture. Thanks for response.

Dear Sir:

Please, that was a natural thing to suggest because of the term marketing is using - "WB preconditioning" implies that it has something to do with white balance, while in fact it is sensor calibration using the mechanism similar to the one used for WB. Many people think ISO is sensor sensitivity, for pretty much the same reason - marketing.

Are IR converted cameras affected in the same way as B&W converted cameras?

Dear Sir:

Could you please rephrase the question, affected by what?

I want to know if the the IR conversion benefits in the same way as the B&W conversion when using the software. Is everything you say about B&W conversion caneras apply to IR conversions as well.

Dear Sir:

If the camera is IR-converted, but colour, you still need to go through demosaicking, and Monochrome2DNG is not applicable.

What would be the best menu and preference option to get the highest resolution DNG from a RAW file with the highest DPI setting possible.

Dear Sir:

The only setting that somewhat of interest here is Preferences -> Data format. If your raw converter can take advantage of DNG in floating point, use that.

If your raw converter deals with black level correctly (allows to open the image, the contrast of the image from the raw converter is good by default, no weak shadows) you can leave Preferences -> Subtract black level unchecked.

Appreciate your reply. Does the conversion bypass the Demosaicing. I was checking out darktable, that has an option under darkroom for demosiac - passthrough (monochrome). When vieweing the render at 200% ,tiny square patterns are visible, which i think is the photosite pattern on the sensor ?
 

Dear Sir:

Does the conversion bypass the Demosaicing

Yes.

When vieweing the render at 200% ,tiny square patterns are visible

I'm afraid we can't give a definite answer without looking at the raw file. Please upload it somwhere and e-mail us a link, mono2dng-feedback@libraw.com

Dear Sir:

Thank you for sending us the file. I don't see square pattern on the DNG converted through MonochromeDNG.

When shooting color (not on this camera), I am able to make improvements in contrast by using the best R,G,orB that has better contrast as a luminance layer. It appears that would not be possible with your program, since the end result is monochrome file. Perhaps the removal of demosaicing artifacts makes the resulting file sharper, so some of my previous workflow may be unecessary. Any thoughts on this? 

Dear Sir:

If your camera is IR-converted through the removal of IR filter, while colour filter array (CFA) is left intact, the files are not monochrome, and this application is not designed to works with such files. If however CFA is removed, there is no R, G, B channels anymore, all pixels are exposed the same way.

Dear Sir,
why can't i open the newly created .DNG files with either darktable or Luminar?
I get an error message every time.
regards,
Patrick M.

Dear Sir:

In Preferences, please try setting Compression to Uncompressed, check that Data format is set to 16-bit integer, tick "Subtract black level".

Thanks for the fast answer which solved the problem.
In preferences, I already had "Data format" set to 16bits and "Substract black level" ticked.
I changed "Compression" setting from "Compressed" to "Uncompressed" as advised, and now no issue anymore, I can now open *DNG files with darktable.
Thanks again,
Regards,
Patrick M.
 

Dear Sir,
after now being able to import  .dng files in darktable, found out that during import process, it seems the ISO value and "35mm lens equivalent" value are lost as they don't show when the JPG saved file is opened up with FastStone viewer.  (If I open directly the same raw file with darktable with demosaicing set to "monochrome" and then save it as a JPG file, the ISO/35mm lens equivavent values are there when I open again the saved .jpg file with the same FastStone viewer).
Regards,
Patrick M.

Dear Sir:

Thank you for letting us knoone of the questions is solved.

Could you please try ticking "Copy vendor Makernotes data to DNG" in Preferences?

What camera are you using?

Hi,
my modified camera for monochrome is a Panasonic G6.
So I get a monochrome2DNG file from a .RW2 file. When opening the .DNG file, the ISO value is in EXIF data (weather "Copy vendor..." is ticked or unticked does not make any difference).
The problem starts when I open the created .DNG file either with: darktable, Luminar 2018, Raw therapee, The ISO value is 0 in all 3 softwares. But if I open the same .DNG file with RawDigger, I can see a @ISO value in the upper left screen "Metadata" and if I click on "EXIF" button, I can find a line for shutter speed, for exposure value, for date created etc... but not for ISO.
Regards,
Patrick Meulnet

Dear Sir:

Could you please upload an original RW2 file to some file transfer service (Dropbox, Google Drive, WeTransfer and some other services are free) and e-mail the link to mono2dng-feedback@libraw.com

Dear Sir,
a link to requested files in my dropox box has been made and sent to you by mail,
regards,
Patrick Meulnet

Dear Sir:

Thank you very much for the sample, the issue is there indeed. It is specific to Panasonic, and we will fix it in the next version.

Just downloaded the latest version but haven't installed yet. I noticed from an earlier version
v0.8.5: Just version update to extend beta expiration time to Sept 1, 2018
that beta expiration date was set to 1st Sept 2018. Has that been extended for the most recent version and if so when is it set to expire?
Thanks

Version 0.9.0 build 25 will expire November 1, 2018.

The Sony version of Capture 1 does not recognize the DNG files output by Monochrome2DNG and the response from Capture 1 was in essence 'too bad'.  I like C1 so I tried a workaround: I first ran the A7r(modified for monochrome visual spectrum) through Adobe DNG converter and then ran the output from the Adobe DNG converter through Monochrome2DNG.  Lastly, I imported the output from Monochrome2DNG into C1.  The files come in with a color cast but appear in proper gray when I check the black and white check box.  I do not see any grid at 400%. 
Now to the question.  Is there anything in my workflow that would adversely affects the output from Monochrome2DNG?  I don't see anything in C1 but I have not yet made a large print.
 
Sneed
 

Dear Sir:

the color cast displayed in C1 means that the RAW data is processed as color (bayer) data, not as monochrome data (produced by Monochrome2DNG). So, debayering/white balance is still performed, and Monochrome2DNG benefits (no debayering, so less moire and higher resolution) are not used.

Could you please upload your files (source, adobe-make, monochrome2dng-made) to some file sharing service  (Dropbox, Google, WeTransfer/free option) and send link to support@fastrawviewer.com for detailed inspection?

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