Huygens image quality lacking?

[morpheus]

I know it is still early days, but do the current images from Huygens represent the best resolution we can expect? So far they seem extremely low resolution and grainy. I didn't expect crystal clear imagery, but what I have seen so far lacks a lot of detail and reminds me of mission footage from the 60's and 70's.

I thought I read an ESA official boasting that Huygens was equipped with cameras that had a resolution 'approaching that of the human eye'. That may be true in relation to frequency response, but the Huygens website states the 'High Resolution Imager' has a resolution of only 160x256 pixels, which is slightly worse than that of my cell phone. I was expecting something like the Mars rover panoramic camera shots.

I understand that taking fancy photo's wasn't the prime purpose of the mission, and there are severe limitations of flying a camera to Titan and operating it in the Titan atmosphere. Even so, considering the PR value of space imagery, is a 160x256 resolution the best ESA could manage when they designed and launched Huygens? :-?

[Saluki]

Remember

1. This is a place much farther removed from the sun than Mars.

2. Titan is shrouded in an atmosphere that is virtually opaque to visible light.

3. Cassini was only within receiving distance for a short period of time. Therefore, the data gathered/sent had to be extremely selective.

Overall, I would call it a great sucess considering the limitations.

[01101001]

Descent Imager/Spectral Radiometer (DISR) aboard Huygens PDF is worth a read.

It's interesting that they started out with a 512x512 pixel CCD, split half of it out for memory, and then crammed the three imagers,via fiber optic bundles, plus spectrometers, photomoter, and solar sensor data, into the remaining 512x256.

Then, the image data got compressed a lot for transmission, from 12 bits/pixel down to 8, then further compressed as JPEG images, betwen 3:1 to 8:1.

They struggled to provide a good number of images and had to sacrifice resolution to do it. I think lack of transmission bandwidth is the ultimate problem.

You can see from the DISR field test images that the resolution is pretty good, but I suspect they didn't compress those images.

[lyford]

Remember the "thumbnails" were always expected to be assembled into panoramas, and not to be taken as individual images themselves. Losing a channel and and turbulence seems to have messed upsome of the complete panoramas, but hopefully they will be able synthesize the missing pixels from other frames.

[Evan]

It's ten year old technology. Computer years are much worse than dog years.

[kucharek]

Data transfer rate was the limiting factor.
And what is "eye resolution"? The only way it would make sense is in terms of angular resolution, which is 1' for the human eye. You cannot say that the human eye has a resolution of x times y pixels. Actually, the human eye is pretty poor. There is only a very small region where you see very sharp. The rest is pretty blurred. It's your brain that gives you the impression that the eye is a great camera in terms of resolution. Actually, it isn't. Same problem as Hugens: Data transfer rate from eye to brain is pretty low.

Harald

[morpheus]

And what is "eye resolution"? The only way it would make sense is in terms of angular resolution, which is 1' for the human eye. You cannot say that the human eye has a resolution of x times y pixels. Actually, the human eye is pretty poor. There is only a very small region where you see very sharp. The rest is pretty blurred. It's your brain that gives you the impression that the eye is a great camera in terms of resolution. Actually, it isn't. Same problem as Hugens: Data transfer rate from eye to brain is pretty low.

Agreed, but the ESA official shouldn't have made the 'resolution approaching that of the human eye' claim, because 99% of people (including myself) got unrealistic expectations.

I am looking forward to seeing the processed panoramic shots which might offer some more context.

[Cugel]

The Jupiter probe on Galileo (1995) didn't have imaging instruments at all. I have the strong feeling (correct me if I'm wrong) that most scientists are not very enthousiastic on pictures because they are extremely expensive in terms of transmission resources. It's basically the same thing with the MER Mars pictures. They're probably the only B/W pictures published on the internet these days. It's even worse than that, many 'scientists' will tell you with dry eyes that it is impossible to take colour pictures. Some will even claim that colour pictures do not exist! You know, its all a trick of your brain. The problem is of course that for 2 dollars and 50 cents you can buy a camera that takes perfect colour pictures of your cat. We're spoiled!

p.s. 7 December 1995, the Galileo website took no less then 250.000 hits that day. Man, how time flies....

[Doodler]

The Jupiter probe on Galileo (1995) didn't have imaging instruments at all. I have the strong feeling (correct me if I'm wrong) that most scientists are not very enthousiastic on pictures because they are extremely expensive in terms of transmission resources. It's basically the same thing with the MER Mars pictures. They're probably the only B/W pictures published on the internet these days. It's even worse than that, many 'scientists' will tell you with dry eyes that it is impossible to take colour pictures. Some will even claim that colour pictures do not exist! You know, its all a trick of your brain. The problem is of course that for 2 dollars and 50 cents you can buy a camera that takes perfect colour pictures of your cat. We're spoiled!

p.s. 7 December 1995, the Galileo website took no less then 250.000 hits that day. Man, how time flies....

Heh, the Jupiter probe also didn't have much to take pictures of. All it would have been was black and white clouds. The spectrograph and windspeed data was more important. Titan had something worth photographing, the ground. THough I do understand your comparison. If there had been a Europa lander, you can bet it would have had a camera.

[Metricyard]

morpheus wrote:

Agreed, but the ESA official shouldn't have made the 'resolution approaching that of the human eye' claim, because 99% of people (including myself) got unrealistic expectations.

The problem here is what you expect and what ascientist expects are very much different. The scientists who design Huygens weren't worried about their pictures meeting THX specifications. They have a lot of data to transmit, with quite a few different experiments running at the same time, with very little bandwidth. They were not planning an Imax movie.

Give them time. With the data that's been collected, I'm sure we'll be seeing a 3d topography of Titan in the future. But don't quote me on that :roll:

[Romanus]

Even if Galileo had carried a camera, there would have been nothing much to see. It entered the atmosphere at a very low angle, and right along the eastern terminator; it would have soon rotated into night, and even if it had been broad daylight, it would have probably fallen through towards unfavorably dark regions of the atmosphere in a short while.