What is causing these 'spots' on my images?

[2Tiggies]

I had no idea how to title this thread! Sometimes, and not in all shots, I noticed bright colored 'spots' especially against a night sky. I know this is going to have some simple answer but I don't know what causes them. They are always red, blue and/or green, interestingly enough.

This was one of the first night time shots I took last year. It was shot in jpg only (yeah, I know, I never thought I would ever have anything worth learning post processing for at the time ) It's the first example that comes to mind because I was so pleased with it when I took it. But the spots are really obvious.


Down the Hatch by 2Tiggies, on Flickr


It's ONLY when there is very low light so I didn't think there was dust on the sensor - but I am clueless. My camera is going up for sale this weekend and if there are any issues with it, and it's not just a beginner user issue, I need to have it sorted out before selling. Any help would be appreciated.

 

[Gianna'sPapa]

Those look like "hot pixels". If your camera has pixel mapping, then in your menu activate that and it should take care of the problem. BTW, what type of camera do you have?

 

[2Tiggies]

Those look like "hot pixels". If your camera has pixel mapping, then in your menu activate that and it should take care of the problem. BTW, what type of camera do you have?

It's a Nikon D90.

 

[2Tiggies]

I will have to go hunt through the menu and see if pixel mapping is there. It doesn't ring a bell as something I've noticed so I may need to haul the manual out

One more question: is it only an issue in low light or is it simply that it's only noticeable against a dark background?

 

[photo_chick]

I will have to go hunt through the menu and see if pixel mapping is there. It doesn't ring a bell as something I've noticed so I may need to haul the manual out

One more question: is it only an issue in low light or is it simply that it's only noticeable against a dark background?

It's there all the time but you're much more likely to notice it in a dark image simply because it stands out.

 

[2Tiggies]

It's there all the time but you're much more likely to notice it in a dark image simply because it stands out.

That's what I wasn't sure of. Thanks

So this is not a camera issue then?

 

[photo_chick]

That's what I wasn't sure of. Thanks

So this is not a camera issue then?

It's a sensor issue. The reason they're always red, green or blue is because all the colors are not firing , so to speak, for those pixels. It takes a combination of all three of those to make the colors. It's an additive color system.

 

[Gianna'sPapa]

To some extent all digital cameras have them. When they come from the factory they are pixel mapped so you don't see them. Yes it is your sensor, but that isn't a major problem to fix. I did a google search and it appears the D90 does not have pixel mapping. Search the internet for some fixes short of sending it back to Nikon. Those spots are easily fixed in PP.

 

[2Tiggies]

It's a sensor issue. The reason they're always red, green or blue is because all the colors are not firing , so to speak, for those pixels. It takes a combination of all three of those to make the colors. It's an additive color system.

Ok that makes sense to my limited grasp of photography. I just need to eliminate the possibility that it's a camera problem that can be fixed as I'd feel awful if I sold it and there was something wrong with it, and it wasn't mentioned in the listing

Edit to add: A quick search shows that it seems to be quite common. There are some options for workarounds for it. I will have a look on Saturday when I have more time.

Thank you for all the info

 

[2Tiggies]

To some extent all digital cameras have them. When they come from the factory they are pixel mapped so you don't see them. Yes it is your sensor, but that isn't a major problem to fix. I did a google search and it appears the D90 does not have pixel mapping. Search the internet for some fixes short of sending it back to Nikon. Those spots are easily fixed in PP.

We posted at the same time (or I edited mine while you posted). Yes, you're right - there is no pixel mapping for the D90. I did fix the spots in LR and it was quick and easy to do, but I posted the image where they were still on there so you could see what I was talking about. I had no idea if they had a name or what was causing them. I learn something new all the time on here!

FWIW, it looks like they are only visible (or more visible) on JPG's, but don't show up on the raw images

Thank you again

 

[photo_chick]

Like Gianna's Papa said, it's easily fixed in editing if your camera doesn't have pixel mapping. My old Rebel has 4 that are red most of the time. I know where they are and it only takes a few seconds to fix them when they're visible.

 

[SrisonS]

FWIW, it looks like they are only visible (or more visible) on JPG's, but don't show up on the raw images

Thank you again

That's funny. With my Canon, I'll sometimes see them on the RAW images, but they go away when converted to JPEG.

 

[2Tiggies]

That's funny. With my Canon, I'll sometimes see them on the RAW images, but they go away when converted to JPEG.

Maybe it's hard to tell from the batches I've examined. I only shot in JPEG until the end of last year thinking I had no need for RAW files So I can't do a comparison with the Disney pics. I have taken some night shots locally in RAW since then and cannot find a single spot on any of them. But when I go back to the Disney ones (all JPEG) I can see the bright spots on all of them where there is a clear sky or 'clean' backdrop to the image I'm curious now. I may need to have a night out with my camera this weekend!

 

[Ladygoldenhair]

Can this effect show on a white background. I had a background of whit walls, they came out with rainbow swirl hue affect.

 

[photo_chick]

Can this effect show on a white background. I had a background of whit walls, they came out with rainbow swirl hue affect.

Post an image. What you're describing sounds like something different than hot pixels.

 

[Gianna'sPapa]

Can this effect show on a white background. I had a background of whit walls, they came out with rainbow swirl hue affect.

That sounds like a dirty sensor, but a picture would help. How you diagnose a dirty sensor is taking a picture of a white piece of paper or blue sky with the aperture closed down. That shows everything on the sensor.

 

[Experiment_626]

Can this effect show on a white background. I had a background of whit walls, they came out with rainbow swirl hue affect.

Was there a texture or repeating pattern on the walls? It sounds like a moiré to me … see http://www.google.com/url?sa=t&rct=...kliqljxnJS2rXSH4B21wyoA&bvm=bv.44770516,d.eWU for more …

Scott