Help with stars and jpeg uploads

[JDDavis]

Looking for tips for how to get stars to show up in jpeg uploads to the web. Let me try to explain...The first image attached is a screenshot of the RAW in Capture NXD and the second is the jpeg that was uploaded to the National Geographic web page. As you can see, more stars are visible in the RAW. The JPEG was a 14mb file, the highest quality that I could export in. Nat Geo has a 20mb file limit on uploads.

Ironically, the 900k jpeg screen capture of the RAW in NXD shows all the stars as I see them on my computer. So why does the exporting of the file to a 14mb jpeg remove stars but the 900k screen capture doesn't? Obviously, exporting to jpeg removes data so it would make sense that faint single points of light would disappear but then why does it like fine on a screen capture?

Follow on question to those that do a lot of star shots. How do you edit and export to ensure max star quality? I'll admit that my exporting knowledge is limited to exporting full res jpegs to online hosting sites and normally I notice very little in quality loss. I don't print much and I'm no pro so I haven't had a need to optimize any of my exporting abilities. I usually just export full size jpegs from Aperture and that's it.

Education, tips, and pointers greatly appreciated!

 

[MCH-1138]

I don't use Capture NX-D, so I don't have a direct answer for you, but the screenshot of the jpeg looks like it has less detail in general, almost as if you had run a gaussian blur over the entire image. Is the exported jpeg significantly downsampled from the original size? Not sure if that would soften the image, but it is at least somewhere to start the discussion...

 

[gnd]

My guess is Nat Geo applied additional heavy compression to what you uploaded. Can you check the filesize of what they show? I bet it's not 14mb ...

 

[JDDavis]

I don't use Capture NX-D, so I don't have a direct answer for you, but the screenshot of the jpeg looks like it has less detail in general, almost as if you had run a gaussian blur over the entire image. Is the exported jpeg significantly downsampled from the original size? Not sure if that would soften the image, but it is at least somewhere to start the discussion...

The jpeg was exported at max quality which produce a 14mb file from a 24mb raw. No doubt something is being lost from the compression and rendering of the jpeg but I've only really taken notice since trying these shots with stars in them.

Here is a jpeg rendered straight from Capture NXD (Aperture is about the same). What I don't get is why does the tiny screen capture show all the stars but not the jpeg? The jpeg straight from Capture is better than Nat Geo though.

 

[JDDavis]

My guess is Nat Geo applied additional heavy compression to what you uploaded. Can you check the filesize of what they show? I bet it's not 14mb ...

I'm sure they do though you'd think it wouldn't be too bad since they allow a 14mb file size. You can't download an image from them and I didn't see anyway to check the size. I don't understand why the screen capture shows more detail even though it is a tiny file. There are tons of amazing shots on the internet with stars in them. I feel like I'm doing it wrong.

For grins I uploaded from Aperture to Zenfolio and did a direct link. It's a 14mb jpeg on Zenfolio that Macrumors is linking to. As you can see it shows a little more detail than the Nat Geo page and the jpeg I loaded as an attachment. It still doesn't show the detail that the screen capture of the RAW does. Should I screen capture all my images and upload them? Probably not. This image is a little different because I've since adjusted the white balance. I think I like it better this way. Not sure.