Domes in Plains South of Ius Chasma

Here is an example of a crater. Its size is about 187 meters across.

On the left is a simple screen shot of a portion of the crater viewed at 1:1.

On the right is the same crater. My view on IAS was zoomed out to 1:8. I saved the image at the highest resolution that IAS allowed.


Then I pulled it up in my normal graphics program, and had to enlarge it in order to give me a side by side comparison of approximately the same size with the 1:1 view.

It is clear from the fact I am having to enlarge the IAS saved version, that the 1:1 detail that SHOULD be there, is not being saved.

As you can see, a tremendous amount of the detail was lost in the IAS saved version:

marsrocks, thanks I got it now. I didn't notice the 1:1 button. I just did it with a dome. What it boils down to is this. When you take a screen capture with the IAS viewer it's going to save approx 512K bytes of data. If you zoom to 1:1 first, assuming the IAS viewer isn't subsampling and is showing you all the data, then if you save a screen view you'll get the full resolution, because it's shown on the screen. On the other hand if you're zoomed out in the IAS viewer and save a screen view <b>and then blow it up to 1:1 in Paintshop</b> you're still only getting approx 512K of data so when you blow it up to the mag that matches 1:1 in the first step, you're going to get mostly empty pixels. Makes perfect sense.

Thanks for pointing out that 1:1 button.

So, the bottom line is look at the dome at 1:1 and that's what it looks like. So, my main point still holds, you just have to be sure you go to 1:1 first.

Kudos to the engineers that made the IAS Viewer.

Joe's image with the Circled No. 3 above is about as good as it gets.

Added Note: Interestingly, 1:1 in the IAS Viewer is the best resolution you can get. If you set something to 1:1, and then click one time with the Plus Magnifying glass, which ups it to 2x, you already see empty pixels. Click twice to 4x and it's very empty. What this means is that you can't improve on an image by moving it over to Paintshop, except maybe qualitatively somewhat by adjusting contrast and brightness.

rd

rd, I think you are exactly right on the IAS viewer. Although it would be a nicer program if you could crop what you want and save any part you wanted at full resolution in tif or bmp.

As far as Joe's pic, I think he could possibly get a more highly detailed view by downloading the grayscale version. It looks like he's got the color version which is 367.5 Mb, while the full grayscale version is 850.3 mb (and should be more than twice as much detail, and plenty more pixels). But otherwise, your point appears to be basically correct. In the color version, a capture or save at 1:1 should give you the ideally best view - of the color version.

So, the only remaining question is: Is the "Full Image" that is under the <b>JP2 Quicklook (IAS Viewer)</b> button the same as the "Full Image" (1.2GB) under the <b>JP2 Products (download)</b> button?

That might be worth a question to them.

rd

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by marsrocks</i>
<br />rd, I think you are exactly right on the IAS viewer. Although it would be a nicer program if you could crop what you want and save any part you wanted at full resolution in tif or bmp.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Yes, this is what I was thinking was happening at first. You're right, that would be the ideal case. I agree with everything else you said.

rd

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">rd: So, the only remaining question is: Is the "Full Image" that is under the JP2 Quicklook (IAS Viewer) button the same as the "Full Image" (1.2GB) under the JP2 Products (download) button?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

rd, they are definitely not the same image, and there is an easy way you can tell this. Pull one of them up in IAS Viewer and move the hand down to the lower right corner. This will tell you the total number of pixels on the x coordinate and the total number of pixels on the y coordinate for that image.

Now, pull up the other image, and do the same.

You will see there are far fewer pixels (and therefore far less detail) in the quicklook image than in the full scale image. Measurements (using .25 meters per pixel should only be done in the full scale image for this reason - there are different numbers of pixels in each).

I believe that the pixel data may also be in the label information for each image as well, although I'd have to check it to be sure that the information corresponds to each image and doesn't just give pixel information pertaining to the full scale image in each label.