Starship Asterisk*

by **Chris Peterson** » Tue Jul 14, 2015 1:34 pm

Javachip wrote:Thank you -- that answers my question. I was just curious as to how these images would compare with what I could take with my own consumer-grade point-and-shoot camera if I were sitting inside New Horizons -- rubbing my hands over the plutonium RTG to keep warm.

Your consumer point-and-shoot would have much lower resolution because of the small aperture. If you attached a consumer DSLR to an 8" amateur telescope, you would have about the same resolution. The LORRI camera has 13 micrometer pixels, which is about 3 times larger than a typical consumer camera, but the extra pixels wouldn't buy you better resolution because that is determined by the telescope optics. Your sensor would be physically larger, so you'd have a larger field of view, but there would be distortion at the edges. Your image would be color, of course, but because of the consumer camera's lower sensitivity the image would be noisier.

by **Javachip** » Tue Jul 14, 2015 11:11 am

Thank you -- that answers my question. I was just curious as to how these images would compare with what I could take with my own consumer-grade point-and-shoot camera if I were sitting inside New Horizons -- rubbing my hands over the plutonium RTG to keep warm.

by **Chris Peterson** » Sun Jul 12, 2015 3:17 pm

Javachip wrote:Does anyone out there know the ISO equivalent speed or sensitivity of New Horizon's imaging sensor in visual light, and what exposure times are typical for the images we are seeing?

ISO specs are more about marketing than they are about anything else. The concept has little relevance for scientific cameras. For those, what matters is the quantum efficiency (the percentage of photons that are recorded), and the dynamic range (the number of photons that a pixel can hold, modified by the intrinsic noise floor).

LORRI uses a thinned, backside illuminated CCD, which means it has a QE approaching 100% at its peak wavelength response (about 700 nm). It's a panchromatic camera (350-850 nm response) that produces monochromatic images. It is designed for typical exposure times of 50-200 ms, which is very fast for an astronomical camera but required because of the rapid motion of the target during flyby. At 100 ms, the image drift on the sensor from the spacecraft pointing stability is on the order of one pixel. The sensor is 1K pixels square (so a 1 MP device). With its 2630 mm focal length, f/12.6 optics it has a resolution of 1 arcsecond per pixel.

The mission goal is to image Pluto with a S/N greater than 100 at flyby.

by **geckzilla** » Sun Jul 12, 2015 10:08 am

Javachip wrote:Does anyone out there know the ISO equivalent speed or sensitivity of New Horizon's imaging sensor in visual light, and what exposure times are typical for the images we are seeing?

I don't know specifics about NH's detector but the exposure times are easily found here:
http://pluto.jhuapl.edu/soc/Pluto-Encounter/index.php

by **Javachip** » Sun Jul 12, 2015 9:34 am

Does anyone out there know the ISO equivalent speed or sensitivity of New Horizon's imaging sensor in visual light, and what exposure times are typical for the images we are seeing?

by **DavidLeodis** » Fri Jul 10, 2015 10:20 pm

In the information about the map that is brought up through the 'dubbed "the whale"' link it states "Continuing to the right, along the equator, we see the four mysterious dark spots that have so intrigued the world...". Wow, that seems a bit of an hyperbole! I have clearly missed the news about the "mysterious dark spots" and I suspect probably so has most of the world!

by **geckzilla** » Fri Jul 10, 2015 7:33 pm

Chris Peterson wrote:Note, however, that these are not raw images (which don't seem to be available). Although they are specified as being unprocessed, the LORRI camera creates 12-bit data, with higher dynamic range than is available with the 8-bit grayscale JPEGs provided. It's unclear if the 12-bit native data has been linearly compressed to 8-bits, or if automatically chosen black and white points have been set to provide better mapping offering more dynamic range. In any case, without more details, I'd be cautious using these JPEG images for any analysis that depends on understanding actual object brightnesses. The actual surfaces of these bodies may be far less contrasty than the images make them appear.

It is going to take a long time to get the raw data. NH compresses the raw data before sending it to us so that we can see it now rather than later. Sometime after the Pluto encounter, it will begin sending the raw data at rates that would make even the most patient internet user from the early 1980's weep, transmitting at a mere 125 bytes per second on a good day.

The eminent Emily Lakdawalla supplied me with this information in her blog post: http://www.planetary.org/blogs/emily-la ... -hard.html

by **ta152h0** » Fri Jul 10, 2015 5:31 pm

we should all sing this APOD title to this music and hoist an ice cold one

https://www.youtube.com/watch?v=ggu0ZqqBq4k

by **Chris Peterson** » Fri Jul 10, 2015 3:09 pm

BMAONE23 wrote:
DavidLeodis wrote:PS. I would be grateful if anyone could please supply a link to the "image snapped on July 7 by the New Horizons" that was then "combined with color data" to produce the image used as the APOD as I don't seem to be fairly readily able to find it.
Click on the "About to be explored" link, then click on the "View LORRI Images" banner

Or go here
http://pluto.jhuapl.edu/soc/Pluto-Encounter/index.php

Note, however, that these are not raw images (which don't seem to be available). Although they are specified as being unprocessed, the LORRI camera creates 12-bit data, with higher dynamic range than is available with the 8-bit grayscale JPEGs provided. It's unclear if the 12-bit native data has been linearly compressed to 8-bits, or if automatically chosen black and white points have been set to provide better mapping offering more dynamic range. In any case, without more details, I'd be cautious using these JPEG images for any analysis that depends on understanding actual object brightnesses. The actual surfaces of these bodies may be far less contrasty than the images make them appear.

by **BMAONE23** » Fri Jul 10, 2015 2:09 pm

DavidLeodis wrote:
geckzilla wrote:Here's one I can agree is terrible. Check out the stray "Text" sitting in the middle. Someone's monitor is too dark to spot it.
http://www.nasa.gov/sites/default/files ... a_swri.jpg
I'm very impressed geckzilla that you were able to spot the "Text" as it took me some while to do so .

PS. I would be grateful if anyone could please supply a link to the "image snapped on July 7 by the New Horizons" that was then "combined with color data" to produce the image used as the APOD as I don't seem to be fairly readily able to find it.

Click on the "About to be explored" link, then click on the "View LORRI Images" banner

Or go here
http://pluto.jhuapl.edu/soc/Pluto-Encounter/index.php

by **DavidLeodis** » Fri Jul 10, 2015 12:51 pm

geckzilla wrote:Here's one I can agree is terrible. Check out the stray "Text" sitting in the middle. Someone's monitor is too dark to spot it.
http://www.nasa.gov/sites/default/files ... a_swri.jpg

I'm very impressed geckzilla that you were able to spot the "Text" as it took me some while to do so

.

PS. I would be grateful if anyone could please supply a link to the "image snapped on July 7 by the New Horizons" that was then "combined with color data" to produce the image used as the APOD as I don't seem to be fairly readily able to find it.

by **Ann** » Fri Jul 10, 2015 5:16 am

Pluto and Charon.

Ann

by **Chris Peterson** » Fri Jul 10, 2015 4:42 am

geckzilla wrote:What is so dishonest about the image that people are going to feel deceived? I think they're more confused than deceived. They really want to know why the images are blurry and there's no processing in the world that can fix that.

I agree.

I, too, worked at JPL on image processing (on the processing technology, not the planetary science). Many images were more heavily processed than today's APOD, because such processing does provide useful information. We'd never use just a single image, of course. So a single APOD image may misrepresent the entire processing and analysis process. But frankly, I don't think that's a big deal. There's nothing about today's image that's deceptive or dishonest.

by **geckzilla** » Fri Jul 10, 2015 2:57 am

Here's one I can agree is terrible. Check out the stray "Text" sitting in the middle. Someone's monitor is too dark to spot it.
http://www.nasa.gov/sites/default/files ... a_swri.jpg

by **geckzilla** » Fri Jul 10, 2015 2:50 am

skyhound wrote:
geckzilla wrote:
skyhound wrote:This is something I know quite a bit about, having once worked in the capacity of doing image processing for a spacecraft team. I stand by my comments.
That makes two of us, then, except I just do image processing as an obsessive hobby. Would I have done this picture differently as well? Probably, but I still think the supplied image is fine. Not that it's really even important for any of us to be qualified to disagree with you, since this is a matter of aesthetics.
I don' see it as a matter of esthetics. It's a matter of honesty and integrity. These images are created for the general public. Most people can't tell the difference between an artifact and real feature, so why give them artifacts? This is not how I would do it, and it's not how many of the people whom I have worked with would do it either.

What is so dishonest about the image that people are going to feel deceived? I think they're more confused than deceived. They really want to know why the images are blurry and there's no processing in the world that can fix that.

Regarding your comparison to your own image to the image release: I think one thing you didn't do with your image is rotate it to get the pole up. The featured image has been rotated and that's degraded it a bit. Every little thing really does seem matter when there are so few pixels and so much is interpolated already. That makes it a little bit jagged along the edges. Anyway, I do see your points, but I still think you are being a little unfair. I've always found Alex Parker's work to be expertly done. It's possible that someone else from the team did this, though. Sometimes press release images get modified by a second party, too.

by **geckzilla** » Fri Jul 10, 2015 2:38 am

bystander wrote:
geckzilla wrote:I don't know where they get their color data from ...
Ralph supplies the color data.

Color Images Reveal Two Distinct Faces of Pluto

I meant the actual data. I know what instrument acquires it. I haven't managed to find a raw release website similar to the one for LORRI. I guess it'll be on the PDS at some point. Thanks, though.

by **skyhound** » Fri Jul 10, 2015 2:05 am

geckzilla wrote:
skyhound wrote:This is something I know quite a bit about, having once worked in the capacity of doing image processing for a spacecraft team. I stand by my comments.
That makes two of us, then, except I just do image processing as an obsessive hobby. Would I have done this picture differently as well? Probably, but I still think the supplied image is fine. Not that it's really even important for any of us to be qualified to disagree with you, since this is a matter of aesthetics.

I don' see it as a matter of esthetics. It's a matter of honesty and integrity. These images are created for the general public. Most people can't tell the difference between an artifact and real feature, so why give them artifacts? This is not how I would do it, and it's not how many of the people whom I have worked with would do it either.

by **skyhound** » Thu Jul 09, 2015 11:46 pm

A very nice image released today.
http://www.nasa.gov/sites/default/files ... _final.png

by **bystander** » Thu Jul 09, 2015 11:41 pm

geckzilla wrote:I don't know where they get their color data from ...

Ralph supplies the color data.

Color Images Reveal Two Distinct Faces of Pluto

by **MarkBour** » Thu Jul 09, 2015 11:14 pm

Boomer12k wrote:Nice...but could have had better focus...
OK...at the right end of "the whale"....I see a guy seated and playing his Trumpet....Ol' Satchmo???

Yes, I thought it looked a bit like Gabriel on a Christmas card (http://www.shutterstock.com/s/angels+tr ... =206025286 ) . But I don't see the feature at all on Chris Peterson's or skyhound's versions, so I doubt it is really there.

by **Boomer12k** » Thu Jul 09, 2015 9:23 pm

Nice...but could have had better focus...

OK...at the right end of "the whale"....I see a guy seated and playing his Trumpet....Ol' Satchmo???

Hoping for better focused views as "we" get closer.

:---[===] *

by **Scott'sMonkey'sUncle** » Thu Jul 09, 2015 9:01 pm

It's blurred a'purpose o'course t' hide th' skyescrapers.

by **geckzilla** » Thu Jul 09, 2015 7:29 pm

Looking elsewhere, here is a picture of Charon from the same dataset. I don't know where they get their color data from so it's black and white. Of course, Charon isn't that colorful, anyway. Feel free to call it overprocessed if you want, but there's not really that much done to it. A friend suggested there is a fetus on Charon. I agree!

by **black_pulsar** » Thu Jul 09, 2015 7:28 pm

alex_ag wrote:The NewHorizons team has just realised a new fantastic image of Pluto some minutes ago:http://mickey-and-friends.wikia.com/wik ... -Pluto.gif

Same color indeed.

by **geckzilla** » Thu Jul 09, 2015 7:19 pm

skyhound wrote:This is something I know quite a bit about, having once worked in the capacity of doing image processing for a spacecraft team. I stand by my comments.

That makes two of us, then, except I just do image processing as an obsessive hobby. Would I have done this picture differently as well? Probably, but I still think the supplied image is fine. Not that it's really even important for any of us to be qualified to disagree with you, since this is a matter of aesthetics.

Starship Asterisk*

APOD: 5 Million Miles from Pluto (2015 Jul 09)

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