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Png Versus Jpeg Image Quality, When generated from a JPEG orginal |
 May 14 2005, 06:33 PM
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Member  Group: Members Posts: 877 Joined: 7-March 05 From: Switzerland Member No.: 186  |
QUOTE (NIX @ May 14 2005, 12:01 AM) Here's an L257 view of Jibsheet. AwalkonMars Still working on the MI mosaic though...  Nirgal, the difference in resolution is indeed an issue but overlapping the images can be a real pain.. Nico  Hi Nico, I just enjoyed your full resolution PNG of east Methuselah (or Jibsheet  ). Exquisite such full resolution! In respect of the size of 25MB I wonder about you generated a PNG-file of it. The orginal pics were sure JPEG - they must be JPEG  Are you sure there would be a visible difference in comparison to a high JPEG version?Note: For the responses in this issue it was opened a new thread in "Imagery & Tech Issues": http://www.unmannedspaceflight.com/index.php?showtopic=1001 This post has been edited by Tman: May 16 2005, 07:55 PM -------------------- |
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May 14 2005, 11:33 PM
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 Chief Assistant Group: Admin Posts: 1409 Joined: 5-January 05 From: Ierapetra, Greece Member No.: 136 |
I think .png is better. Have not tested that extensively though. Anyone? Originals of course .jpg. I'm just used to convert fullres and 50% to .png and thumbnails to .jpg
There's some awesome stereo's in that pan too btw  Nico -------------------- photographer, space imagery enthusiast, proud father and partner, and geek.
http://500px.com/sacred-photons & |
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May 15 2005, 09:13 AM
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Chief Assistant Group: Admin Posts: 1409 Joined: 5-January 05 From: Ierapetra, Greece Member No.: 136 |
.png and .jpg have their particular advantages but the main thing driving me right now to use .png is that saving and re-saving an image will not degrade quality, unlike to even highest quality .jpeg.
I might add some .jpg versions in the future for 100%'s like I do occasionally for 25% images but I'll also keep the .png's. Nico
-------------------- photographer, space imagery enthusiast, proud father and partner, and geek.
http://500px.com/sacred-photons & |
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May 15 2005, 05:30 PM
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Member Group: Members Posts: 877 Joined: 7-March 05 From: Switzerland Member No.: 186 |
QUOTE (NIX @ May 15 2005, 11:13 AM) .png and .jpg have their particular advantages but the main thing driving me right now to use .png is that saving and re-saving an image will not degrade quality, unlike to even highest quality .jpeg. I might add some .jpg versions in the future for 100%'s like I do occasionally for 25% images but I'll also keep the .png's. Nico Agree, that's a good plan BTW, my connection is fast enough, but I've thought it needn't be, also for your upload consumption. Regarding PNG or JPEG generated from JPEG orginal pics, I remember as I was looking for Bonneville its visibility at West Spur (around sol 220), I tried for best visibility with PNGs from JPEG orginal pics by ~4 times magnified and higher. But I only could determine the PNGs save somewhat more color gradients without any better sharpness. Therefore I think only differences in color gradient could catch someone's eye. But these images of Mars get rather little color gradients and little differences of color. If there would be a flower meadow, then probably would it be visible. 
This post has been edited by Tman: May 15 2005, 05:46 PM -------------------- |
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May 15 2005, 06:30 PM
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 Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
Ummm... correct me if I'm wrong, but doesn't this PNG vs. JPG discussion belong in the Imagery Issues forum? I glance through that forum, but as someone who's more interested in the geology and meteorology on Mars than in the technical details of how to play with the pictures, I guess I'd like to be able to glance through the imagery issue discussions separately....
-the other Doug -------------------- “The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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