Check your version of autoconf and compare to AC_PREREQ in aclocal.m4. Try re-installing autotools if something doesn't work.
On my focal 20.04 LTS, following https://www.libraw.org/docs/Install-LibRaw.html

$ apt-cache policy pkg-config
pkg-config:
  Installed: 0.29.1-0ubuntu4...
$ apt-cache policy automake
automake:
  Installed: 1:1.16.1-4ubuntu6...
$apt-cache policy libtool
libtool:
  Installed: 2.4.6-14...
$ autoconf -V
autoconf (GNU Autoconf) 2.69....
$ cd
$ git clone https://github.com/LibRaw/LibRaw.git
$ cd LibRaw
$ autoreconf --install
$ ./configure
$ make
$ bin/raw-identify 
Usage: /home/ib/LibRaw/bin/.libs/raw-identify [options] inputfiles
Options:
	-v	verbose output
	-w	print white balance
	-u	print unpack function
	-f	print frame size (only w/ -u)
	-s	print output image size
	-h	force half-size mode (only for -s)
	-M	disable use of raw-embedded color data
	+M	force use of raw-embedded color data
	-L filename	read input files list from filename
	-o filename	output to filename

Yes, I checked that: automake-1.15

I will try to reinstall.

Thank you anyway for your quick reply!

Sorry, I was confused. Repeated it so many times that I got a bit lost. Here is what happens:

./configure seems to work

make produces some warnings and errors:

configure.ac:16: error: possibly undefined macro: AC_SUBST
If this token and others are legitimate, please use m4_pattern_allow.
See the Autoconf documentation.
configure.ac:41: error: possibly undefined macro: AC_MSG_WARN
make: *** [Makefile:651: configure] Fehler 1

ignoring these, sudo make install produces the aforementioned error:

configure: WARNING: libjasper not found
./configure: line 12807: syntax error near unexpected token `ZLIB,zlib,'
./configure: line 12807: ` PKG_CHECK_MODULES(ZLIB,zlib,'
make: *** [Makefile:648: config.status] Fehler 2

Thanks! Jan

Hi, just ./configure.

Hi, same problem here, but different line:

checking for jas_init in -ljasper... no
configure: WARNING: libjasper not found
./configure: line 12807: syntax error near unexpected token `ZLIB,zlib,'
./configure: line 12807: ` PKG_CHECK_MODULES(ZLIB,zlib,'

any ideas? Thanks very much, Jan

Thank you for the clarification, I was confused by the documentation, but now I understand.

From the documentation (which can be sometimes confusing, I agree): "After call to unpack() only one of *_image fields is non-NULL."

LibRaw supports most DNG files (all DNG files if compiled w/ DNG SDK)

No cameras produces floating-point data raw images (yet?), one may use (different) HDR-convertor software to create floating point images.

Regarding color3/color4:
- full-color images unpacked by LibRaw itself are (mostly) color4_image, you may use any full-color (not bayer) RAW file for that, for example Canon sRAW/mRAW CR2

- full-color images unpacked by 3rd-party decoders (Adobe DNG SDK, RawSpeed) are usually color3_image images. You may use the same sRAW/mRAW CR2 and RawSpeed decoder (via LibRaw)

Please share some example file(s)

USE_ZLIB USE_JPEG must be used together when using DNG_SDK

Hi, I hope you're doing fine. Can you please add support for Xiaomi mi 10t. I've captured insane astrophotographs using this phone and it also has burst long exposure mode but deep sky stacking isn't possible without you. the outcome i can either do is trailing OR timelapse of milky way. This phone also has astrophotography mode in builtin camera.
Thanks.