Why NASA photos always in B/W

I know this is really off topic, but I was just reading about the Mars rovers, and the Phoenix Mars Lander and couldn’t help and wounder why the photos are in B/W. Didn’t the mars rovers send back color photos or were they orginially in b/w only being modified on earth?

Would b/w photos be smaller file sizes? I thought quality was based on image resolution, not color output.

Anyone?

Thank you,

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Comments

undomiel

If you're applying compression you can compress black and white photos (even lossless) a whole lot better than colour. Plus if you are stripping out the other colour channels you wouldn't need as much information per a pixel. It depends upon how they are encoded i.e. colour you have to encode RGB as three separate bytes while black and white you can just encode intensity as one byte.

datchcha

undomiel wrote:

If you're applying compression you can compress black and white photos (even lossless) a whole lot better than colour. Plus if you are stripping out the other colour channels you wouldn't need as much information per a pixel. It depends upon how they are encoded i.e. colour you have to encode RGB as three separate bytes while black and white you can just encode intensity as one byte.

Wow...didn't know there was that much to it....thanks.

snadam

its called 'the red planet' , use your imagination

kidding!

pwjohnston

If you have photoshop try creating a psd file of your favorite image in CMYK at 300dpi in color and then strip the color and save it in the same folder in B/W. The file size difference should be dramatic.

JDMurray

It's easier for the human eye to see detail in grey scale (intensity) images than in tens-of-thousands of colors too.

http://en.wikipedia.org/wiki/Mars_Reconnaissance_Orbiter#HiRISE_.28camera.29

http://en.wikipedia.org/wiki/Phoenix_%28spacecraft%29#Robotic_arm_and_camera