Legacy ImageMagick Discussions Archive

After some experimenting, I succeeded in piping dcraw's output to ImageMagick, see https://imagemagick.org/discourse-server/viewtopic.php?f=1&t=36517&p=167986&hilit=dcraw+piping#p167986.

As an alternative, I could probably edit the dcraw parameter settings in delegates.xml. However, there is only ...

This is the official answer of the development team:

The TIFF delegate library has support for EXIF but we found it to be buggy. It often caused faults and exposed a security vector. We eventually disabled EXIF. Until we see improved support for EXIF in the TIFF delegate library, you will instead ...

I just ran into the same problem when converting RAW into TIFF, see https://imagemagick.org/discourse-server/viewtopic.php?p=167971#p167971.

It took me some time to find out that the problem was created solely by ImageMagick that deleted the Exif information during the conversion TIFF --> TIFF. And ...

I tried the piping version -- yesterday on my computer at home, running Windows 10, 64 bit and just now on my office computer running Windows 7, 32 bit.

The latter has just thrown a different error when using IM's version of dcraw (9.27): dcraw laments that there is 'no disk'. Again, the ...

Yes, this does the trick!
But, as far as I see, only with the original version of dcraw. If I use IM's modified version (which has the additional option -O) instead, IM reports that it cannot read the input file:
magick: improper image header `C:/Users/Hugemann/AppData/Local/Temp/magick ...

I am using a Windows appliction that calculates luminance from RAW images taken by a calibrated camera. This application allows me to define two command lines that convert the original photo into an 8-bit-TIFF for display on the monitor and a 16-bit-TIFF for evaluation of the luminance. The default ...

I think our misunderstanding arises from the point that your suggested delegate-command
<delegate decode="LUM2" stealth="True" command="cmd.exe /c (F:/pictures/dcrawag.exe -q 3 -o 0 -4 -r 1 1 1 1 -S 65535 -T -O &quot;%u&quot; &quot;%i&quot;) &amp; (magick TIFF:%u -colorspace Gray -resize 600x600 %o ...

IM has no mechanism for taking arbitrary options from its command line and passing those to the delegate.

I don't want to pass parameters to the delegate; I would like to be to be free of choice in regard to the operations that magick performs on the temporary file, for example scaling, a 3x3 ...

Although your suggestion works and solves my actual problem, I am not quite convinced: The result is pretty much the same as that of the batch file:
C:\Programme\ImageMagick7\dcraw.exe -q 3 -o 0 -4 -r 1 1 1 1 -S 65535 -T -O "%~dp1temp.TIF" %1
magick "%~dp1temp.TIF" -distort barrel "0.0099 -0.0678 0 ...

I have a similar problem under Windows 10, 64 bit:
I would like to develop a Sony RAW photo (*.arw) with my own settings and apply a lens correction to it. Following the hint given in this thread I arrived at:

<delegate decode="LUMINANCE" stealth="True" command="dcraw.exe -q 3 -o 0 -4 -r 1 1 1 1 ...

I think that only the programmers could really answer that question. My impression is that this option just does nothing at the moment. Perhaps one could re-define it in a way that it really does what it claims, i.e. leaving everything, including the DQTs, untouched.

Checking out the other options ...

The documentation is out-of-date. We preserve sampling factor and image quality but not the quantization tables.

The Usage page https://www.imagemagick.org/Usage/formats/#jpg_write still hasn't got it quite right IMHO, as it skips the point that these settings are kept automatically.

However ...

I have just been experimenting with this option on my Windows computer, running IM 7.0.8-23 Q16 x64:
magick -size 256x256 -depth 8 -seed 1000 plasma:fractal -define jpeg:q-table="C:\Temp\Erich\table.xml" plasma_my.jpg
checking the DQT afterwards with JPEGsnoop (https://www.impulseadventure.com ...

I took a closer look at the code and found out myself: Basically, IM calculates the sum of all DQT entries and compares it directly to the sum of the IJG table entries, which is pre-calculated and stored in the vector sums[101]. The same is done for the sums of the two table entries no. 2 and 53 ...

I would like to know how IM estimates the JPEG Quality.

I took a look at the code in jpeg.c, and it obviously calculates it from the DQT (around line 922). I know about the way how quality is translated into DQT as suggested by the IJG. But to my knowledge the IJG made no suugestion for the other ...