HIRSE is not capable to take pictures of 25 cms/pix but up to 1 meter / pixel.
But, it takes good color pictures. The latest color picture taken by HIRSE from MRO to the Constellation Southern Cross as an example:
Click here
HiRISE can image in three colors: green, red, and near-infrared, so the colors are not exactly as we see them with our eyes. The image shown here is a small portion of the full image, which is 20,000 x 35,000 pixels or 700 mega-pixels.

More technical details about HIRSE
Advanced technical details about HIRSE


Rodolfo

I am not sure if the use of "pix" and "pixel" is referring to same thing. But from the first link in post --

"HiRISE will return surface images that contain individual basketball-sized pixel elements (30-60 centimeters, or 1 to 2 feet wide), allowing surface features 4-8 ft across to be determined (resolved)."

I.e., several pixels are required to resolve an object given a single image. E.g., given a uniform background, a single pixel that is different than the background could indicate an object or could be noise. If multiple images of the same target area could be integrated, smaller objects can be resolved.

1 m/pixel, isn't that the same as Mars Global Surveyor?

The pixels will be 25-30cm - but they use that to establish that it will be able to 'resolve' items of 1m



What you can 'resolve'and what your resolution are, are two different things.

For comparison, MGS MOC is typically 1.5m/pixel, although CPROTO makes that 0.5m/pixel downtrack - hence the non square pixels in my simulation

Doug

Doug's point about resolution is very important... this is often a source of confusion.

If a pixel is 1.5 m across, an object 1.5 m across and squarely on a pixel will just show up as one point, so it can be detected but it can't be interpreted - is a bright spot a boulder, a flat rock outcrop, a dune, a slope catching the sun, a landed spacecraft? Also, a 1.5 m object not perfectly aligned with the pixels will intrude into several of them, making it look larger (but reducing contrast).

So people often use other measures of resolution. The most common is the 'line pair' - two pixels, in other words. The 'effective resolution' of the 1.5 m/pixel image is 3 m, meaning you can make a reasonable guess at what you are looking at if it's two pixels across. The USGS used to have a rule of thumb that an object had to be at least 5 pixels across for reliable interpretation.

Phil

The way I figure it, that to 'resolve' something, you have to be able to say that there will be more than one pixel that is nothing except that object. The CPROTO images of the rovers are cool, but no one pixel is nothing-but-rover, they'll all just about include a big chunk of ground, and a bit of rover in the mix, contributing to the brightness of that pixel.

So - say you have a 1m resolution - and a 1x1m object, you could be REALLY unlucky and have the join of 4 pixels in the middle of your object and all you would have is 4 pixels that are 75% ground and 25% object. You've not resolved it

If you had a 2 x 2m object, there's no way in which the 'pixels could fall' where by you dont have at least one pixel that's totally saturated with the object and nothing else.

But to have be sure of what you're looking at - to have multiple pixels of the object in question - (and if you're have multiple pixels then it's going to have to be 2 x 2 pixels of it ) then you're looking at a minimum object size of 3 x 3 m - that's 3 x the 'resolution' of the camera.

So - transpose that onto the Peoples Camera (HiRISE) - and you have 3 x 30cm, which is, as near as makes no difference, 1 metre Any 1x1m object is certain to be the only source of photons in at least 4 pixel elements when you have a 30 x 30cm resolution.

I dont think there's any hard and fast rules on this. Like much imaging, it's a judgement call at the end of the day. I think my two simualtions are fairly representitive of the camera's abilities given perfect conditions. SS loved it when I gave him a little print out in a frame as a thankyou for his updates and hardwork on behalf of this place. I dont think the HiRISE team had done anything like that ( Steve's on the science team for it ) - and it certainly packed some wow factor. I dont think there will be a single HiRISE image that doesnt make you go "WOAH!"

That's my non-expert guestimated take on the situation anyway. It sort of makes sense...ish

Doug