How to convert CR2 to JPG or PNG?

Question

I need to convert a lot of CR2 photos to either JPG or PNG, no editing. How to do this?

Answer 1

I'll go a different route... Use ufraw-batch not ufraw.

sudo apt-get install ufraw-batch

## This will output (not replace) the file with a new extension.
## foo.CR2 exported to foo.png
ufraw-batch --out-type png *.CR2

See ufraw-batch --help and man ufraw-batch for more info.

Answer 2

ufraw alternatives

The accepted answer recommends to use ufraw, but ufraw's development has ceased as of June 2015 and it's not supported by current Ubuntu releases. See Ubuntu Bugtracker, which recommends darktable or rawtherapee as alternatives. Both tools are GU tools, but it is possible to use them from CLI.

darktable: manual, man page

Batch processing example:

for pic in *.CR2
do
     darktable-cli "$pic" "$(basename ${pic%.CR2}.jpg)"; 
done

rawtherapee: manual

Answer 3

Ufraw

you can convert .cr2 to .jpeg by ufraw.

sudo apt-get install ufraw

Right click on the file and select open with ufraw.

** You can also import them to Gimp with gimp-ufraw and then export as .png or .jpeg.

sudo apt-get install gimp-ufraw

Answer 4

For another alternative, use mogrify:

mogrify -format png *.cr2

Answer 5

Try nconvert

As command line tool OR xnconvert as GUI tool

Answer 6

The method that really worked for me:

You need dcraw and ppmtojpeg (install with apt)

for i in *.CR2; do dcraw -c $i | ppmtojpeg > $1.jpg; echo $i done; done

What it does: First convert CR2 to PPM with dcraw passing the output to ppmtojpeg which converts to JPG.

I found this here

Answer 7

Create a bash file like foo.sh and execute as ./foo.sh in command line:

#!/bin/sh

for i in $(ls)
do
ufraw-batch --out-type png $i
echo "conversion done $i"
done

Answer 8

I had trouble with ufraw since it produces a segmentation fault on elementary OS (see https://bugs.launchpad.net/ubuntu/+source/ufraw/+bug/1768855). I combined your answers (thanks!) and finally got a working version.

First get the right command for exiftool (as mentioned by Rafael):

exiftool -s2 -all -b -X -fXMP:XMP test.RAF  | grep Preview

which is in my case not -Composite:PreviewImage but:

File:PreviewImage

So you can use the batch script from Abu:

#!/bin/sh
for i in *.RAF
do
exiftool -File:PreviewImage -b $i > $i.jpg
echo $i
done

Answer 9

.cr2 files are apparently some kind of Canon digital camera raw format. Maybe that's what CR stands for?--"Canon Raw".

Anyway, I just recovered a bunch of them from a corrupted SD card from a digital camera, using ddrescue and photorec (installed by sudo apt install testdisk, and here's how I just converted hundreds of recovered .cr2 files to .png and .jpg images:

Update after writing this answer:

[I need to experiment more with this too]

CR2 files appear to be valid TIF files too, so you might also try simply changing the file extension from .cr2 to .tif and then using tools to convert from .tif to .jpg or .png! I just renamed the file extension from .cr2 to .tif and double-clicked it and my image viewer in Ubuntu 20.04 was able to open it just fine.

How to convert a single .cr2 image to a .jpg or .png image

Tested in Ubuntu 20.04.

# First, install ImageMagick
sudo apt install imagemagick
strip off the .cr2 extension from your file (this is required for some reason
to make convert work)
mv myimage.cr2 myimage
Create a JPG from that image.
- This creates myimage.jpg. The original myimage image remains intact.
convert myimage myimage.jpg
Create a PNG image from that image
- This creates myimage.png. The original myimage image remains intact.
convert myimage myimage.png

That's it!

Note: if convert won't work, try the fix I mention in my answer here.

How to batch convert hundreds of .cr2 images into .jpg or .png images

In my case, I needed to convert hundreds of images from .cr2 to .png. Here is how I did that as fast as possible, using all 8 of my CPU cores at once:

cd path/to/all/of/your/cr2/images
Move all .cr2 images into a "cr2" folder
mkdir cr2
mv *.cr2 cr2
cd cr2
strip the extension (convert won't work if you don't do this first, for some
reason)
How to strip file extensions in bash:
https://unix.stackexchange.com/a/180272/114401
for file in *.cr2; do mv -- "$file" "${file%%.cr2}"; done
Convert them all to PNG images now!
- I learned about xargs from here:
https://stackoverflow.com/a/25532027/4561887 and in my answer here:
https://stackoverflow.com/a/76910116/4561887
- Note: -P "$(nproc)" says to spawn as many parallel processes as you have
CPU threads, since nproc returns the number of hardware threads
(hyperthreaded "processors", or "cores") your computer has. So if nproc
shows you have 8 hardware threads, this will spawn 8 simultaneous convert
operations to speed this up!
ls | xargs -n 1 -P "$(nproc)" -I% convert % %.png
When done, move all produced .png images to a "png" dir one level up, at the
same level as the "cr2" dir we are currently in
mkdir ../png
mv *.png ../png/

Going further: how to recover images from a corrupted camera SD card, memory card, drive, or disk (or just deleted files)

(This is how I got all of my .cr2 files above).

See my answer here: Unix/Linux undelete/recover deleted files

References

1. Converting images from .cr2 to .png or .jpg:
   1. Google search for "linux convert .cr2 to jpg"
      1. Very useful!: where I first learned about using convert to convert .cr2 images to .png. I also learned here that you have to strip the .cr2 extension first to make it work!: https://www.linuxshelltips.com/convert-raw-camera-image-to-jpeg-in-linux/
   2. Where I learned how to strip file extensions in bash: https://unix.stackexchange.com/a/180272/114401
   3. Where I learned how to use xargs to parallelize operations on files listed by ls: https://stackoverflow.com/a/25532027/4561887
2. My answer where I used xargs with -P "$(nproc)" to unzip many password-protected files at once, in parallel: Stack Overflow: unzip password protected zip in unix

Answer 10

You could also program a simple loop in the console.

For example (using the fish console), and assuming the active directory only has RAW files.

set files (ls)
for i in $files
    dcraw $i
end

or

set files (ls)
for i in $files
    ufraw-batch --out-type=tif --out-depth $i
end

I use ufraw-batch that way because it often leads to an error, see https://bugs.launchpad.net/ubuntu/+source/ufraw/+bug/1768855 .

Answer 11

In case you need preview the photos as an initial filtering step, here's what I do

1. install packages: sudo apt-get install -y dcraw netpbm
2. extract all thumbnails as jpeg: for i in *.CR2; do dcraw -e $i ; done
3. let my wife filter the images (the jpgs)
4. run the following .py script (python3 rm_filtered_cr2.py):

   import os
   files = os.listdir()
   for cr2_file in files:
       if cr2_file.endswith('.CR2'):
           thumbnail_file = cr2_file.replace('.CR2', '.thumb.jpg')
           if not os.path.exists(thumbnail_file):
               print("removing %s" % cr2_file)
               os.remove(cr2_file)

Answer 12

Use:

exiftool -Composite:PreviewImage -b photo.CR2 > photo.jpg

Longer answer:

ufraw-batch conversion quality is very bad. Imagemagick uses ufraw under the hoods (unfortunately). dcraw is better, but still not great. The best solution I found out was to use exif to extract PreviewImage metadata. I believe that's generated by the camera itself.

Ref: https://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=6936&sid=9548c421f1bd69f192e632d06ca03dff&start=30#p130949