ERROR: Unknown extension to write to: .pbm

[dclunie]

Compressed a single bit PBM image:

% FLIF-0.3/src/flif x.pbm x.flif

failed on decompress:

% FLIF-0.3/src/flif -d x.flif x_rt.pbm

ERROR: Unknown extension to write to: .pbm

[bjorn3]

#554

FLIF development has stopped since FLIF is superceded by FUIF and then again by JPEG XL (https://jpeg.org/jpegxl/index.html), which is based on a combination of Pik and FUIF.
A royalty-free and open source reference implementation of JPEG XL is available on GitLab.

[bjorn3]

You can find the full list of supported output format here:

FLIF/src/image/image.cpp

Lines 69 to 95 in aad2083

	if (ext && !strcasecmp(ext,".png")) {
	return !image_save_png(filename,*this);
	}
	if (ext && !strcasecmp(ext,".pnm")) {
	return image_save_pnm(filename,*this);
	}
	if (ext && !strcasecmp(ext,".pgm")) {
	return image_save_pnm(filename,*this);
	}
	if (ext && !strcasecmp(ext,".ppm")) {
	return image_save_pnm(filename,*this);
	}
	if (ext && !strcasecmp(ext,".pam")) {
	return image_save_pam(filename,*this);
	}
	if (ext && !strcasecmp(ext,".rggb")) {
	return image_save_rggb(filename,*this);
	}
	if (ext && !strcasecmp(ext,".icc")) {
	return image_save_metadata(filename,*this,"iCCP");
	}
	if (ext && !strcasecmp(ext,".xmp")) {
	return image_save_metadata(filename,*this,"eXmp");
	}
	if (ext && !strcasecmp(ext,".exif")) {
	return image_save_metadata(filename,*this,"eXif");
	}

[dclunie]

I thought JPEG-XL did not support single bit images (which FLIF does a nice job of compressing)

[jonsneyers]

JPEG XL does support 1-bit too. It's probably even better for them, since it has JBIG2-style "pattern" features. The current JXL encoder hasn't really been tested or optimized much for that particular case though.

FLIF doesn't save .pbm, you can save as .pgm and then convert it with e.g. ImageMagick.

[dclunie]

My tests so far indicate that the current JPEG XL encoder did not do as well on single bit images as FLIF, and I can't test that round trip is lossless because there is a bug during decoding (which I previously reported to Jan, with you cc'd).

I have given up on JPEG XL until this gets fixed, and it won't be included in my upcoming paper on single bit compression as a result.

David