[Cin] zscale's tonemapping on input

[Andrea paz]

I find this:

/usr/bin/ld: /tmp/ffconf.LBw6bqQB/test.o: in function
`check_zimg_get_api_version':
test.c:(.text+0x3): undefined reference to `zimg_get_api_version'
collect2: error: ld returned 1 exit status
ERROR: zimg >= 2.7.0 not found using pkg-config

But here I stop for total incompetence.