Bash + ImageMagick, 60 77 bytes

convert <(echo P3 3 1 255 0 85 164 255 255 255 239 65 53) -sample 78x52\! a

(ugh, +17 chars due to color requirements I didn't notice earlier...)

Exits with an error, but still satisfies the requirements of the challenge.

Outputs to the file a, in netpbm format:

llama@llama:~$ convert <(echo P3 3 1 255 0 85 164 255 255 255 239 65 53) -sample 78x52\! a
convert: unexpected end-of-file `/tmp/magick-26005q5lLEsKYnuOU' @ error/pnm.c/ReadPNMImage/1360.
llama@llama:~$ file a
a: Netpbm image data, size = 78 x 52, rawbits, pixmap

Can also output in PNG, if you change the filename to a.png (+4 chars).

Output:

Bash + ImageMagick, 60 77 73 bytes

convert -sample 78x52\! - a<<<"P3 3 1 255 0 85 164 255 255 255 239 65 53"

(ugh, +17 chars due to color requirements I didn't notice earlier...)

Outputs to the file a, in netpbm format:

llama@llama:~$ convert -sample 78x52\! - a<<<"P3 3 1 255 0 85 164 255 255 255 239 65 53"
llama@llama:~$ file a
a: Netpbm image data, size = 78 x 52, rawbits, pixmap

Can also output in PNG, if you change the filename to a.png (+4 chars).

Output:

Bash + ImageMagick, 60 bytes

convert <(echo P3 3 1 1 0 0 1 1 1 1 1 0 0) -sample 78x52\! a

Exits with an error, but still satisfies the requirements of the challenge.

Outputs to the file a, in netpbm format:

llama@llama:~$ convert <(echo P3 3 1 1 0 0 1 1 1 1 1 0 0) -sample 78x52\! a
convert: unexpected end-of-file `/tmp/magick-26005q5lLEsKYnuOU' @ error/pnm.c/ReadPNMImage/1360.
llama@llama:~$ file a
a: Netpbm image data, size = 78 x 52, rawbits, pixmap

Can also output in PNG, if you change the filename to a.png (+4 chars).

Output:

Bash + ImageMagick, 60 77 bytes

convert <(echo P3 3 1 255 0 85 164 255 255 255 239 65 53) -sample 78x52\! a

(ugh, +17 chars due to color requirements I didn't notice earlier...)

Exits with an error, but still satisfies the requirements of the challenge.

Outputs to the file a, in netpbm format:

llama@llama:~$ convert <(echo P3 3 1 255 0 85 164 255 255 255 239 65 53) -sample 78x52\! a
convert: unexpected end-of-file `/tmp/magick-26005q5lLEsKYnuOU' @ error/pnm.c/ReadPNMImage/1360.
llama@llama:~$ file a
a: Netpbm image data, size = 78 x 52, rawbits, pixmap

Can also output in PNG, if you change the filename to a.png (+4 chars).

Output: