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How to remove water / oily stains from a dSLR sensor


Archbob

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Hi,
I've been photographing across Nebraska and Colorado the last few days and sleeping in the car so I have not had time to look/process my images. Unfortunately, I did not see dust get onto my sensor and now in the top left corner of many of my images, there are various black dots and I need to know to to remove them. They cover too big an area for me just to crop and using the clone stamp tool just does not work because the background is not a solid color. I've uploaded an example here(will clean out my sensor tomorrow so this does not happen in the future).

I have only photoshop cs3 and don't have lightroom.

Please help.

Do I have to get a newer version of Photoshop to remove these?
 

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Archbob

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Clone stamp does not work because the background is not a solid color. The spots are not minute in size.
 

Rich54

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I did this with the patch tool. Took 5 minutes. (Not sure if if CS3 has the patch tool. The spot healing tool also worked, but not quite as well.)

final1.png
 

Tom Mann

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Hi Archbob - Welcome to PSG. FWIW, the slightly darker, very soft-edged areas in the upper RHC of your image look more like dried / smeared water or oil spots on the sensor, not dust. At f/11, the aperture at which you took this picture, dust on the sensor would show much, much sharper edges, more structure, and the majority of dust particles usually are much smaller than what you have.

The reason for making this distinction is because if the problem only involved a few pixels, the automated methods of dust spot removal usually work quite well. However when problems occupy this much real estate in the image, I'm afraid you are probably stuck removing them manually. The distinction is also important in terms of how to remove them from the sensor -- specifically, if they indeed are dried water spots, you won't be able to just blow them off.

The more recent versions of LR (v5, and after, I think) do have a very nice automated tool to remove dust and other spots that remain in the same position from frame to frame. Here are two links to articles about this tool:

http://digital-photography-school.com/how-to-remove-dust-spots-from-multiple-photos-in-4-steps/
http://photographyessentials.net/lightroom-auto-spot-removal/

Unfortunately, while this tool does have some intelligence built in, it is not magic, and when spots this size occur in areas with important features / texture, you probably won't be happy with its result. When problems occur in important / textured areas, you are better off learning how to fix the area manually using either:

1) The patch tool - for relatively easy to fix problems with irregularly shaped boundaries.

2) The content aware fill tool - for more difficult problems (also with irregular boundaries)

3) The spot healing brush tool - in either conventional or content aware mode ... best with simple / small circular areas.

4) The clone tool.

My guess is that Sam recommended #4 because of the old version of PS that you own. However, if you are serious about working on this problem and your time is valuable, I would (at minimum) rent the newest version of PS for a month or two (at a very reasonable cost) because it includes all the new tools, as well as includes refinements to older tools.

The difficult in using the above tools ranges from trivial, very easy to use -- almost one click fixes, all the way to being quite difficult and requiring lots of experience. It all depends on what the spot is covering, how big it is, and if you can find other areas of the image that you can steal pixels from. Fixing the spots in the sky in image you posted is trivial - I simply used #3 in content aware mode. It took me under 1 minute to get rid of these spots. Other images can be much, much harder.

So, if you have lots of images of the latter type, prepare to Google tutorials on the use of these tools and develop your skills by practicing.

HTH,

Tom M

PS - Because this thread is about water marks, not dust, I'm going to change the title of the thread for anyone looking for info on this topic in the future.
 

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Tom Mann

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PS #1 - FWIW, I used PS CC 2014 - mostly 'cuz I happened to have it up and running when I started on my little demo.

PS #2 - I can guarantee you that any of the tools I mentioned, including the clone stamp tool will work. However, there is technique involved in using any of these. They are not one-button-fixes. With the clone stamp, you have to work slowly at low opacity. IMHO, the spot healing brush in content aware mode is the quickest for something this simple. There is essentially no texture to the background (sky) near the water spots.

Tom M
 
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Tom Mann

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To illustrate that Sam, who is *extremely* knowledgeable in Photoshop and one of the other moderators here, gave you good advice when he recommended the stamp/clone tool, below, I illustrate how one can remove the water spots using nothing more than the clone tool. It took me about 3 minutes to clean up this area. So, it's a bit slower than my preferred method, but still works just fine. Other than speed, the other reason I prefer content aware based methods, or even the patch tool is that they tend to preserve texture (eg, film grain / sensor noise) better than multiple applications of the clone/stamp tool, which tends to smooth out texture.

I really don't understand your repeated comment that the background is not uniform. It shouldn't be a problem at all once you have the technique down. In the grand scheme of things, the blue sky background in this picture is about as nice and uniform a background for cloning as one can ever ask for. The trick is to use the tool at low opacities. I used it at ~ 30% (with a very soft brush). I used such a large number only because I was rushing and know what I can get away with, but opacities of 10% or below are more usual. Such low opacities force one to work slowly. You should sample from different source areas as you are working.

Also, never work on the original layer. Either clone to an initially blank layer, or if you are not familiar with that approach, work on a duplicate layer. This way, if you make an error, it's easy to erase areas you don't like without erasing the original.

HTH,

Tom M

tjm01-acr-ps02a_crop_fix_with_only_clone_tool-for_GIF.gif
 

IamSam

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Clone stamp does not work because the background is not a solid color. The spots are not minute in size.

Tom is correct. Like Rich, I wasn't sure what tools were available in CS3.

I won't add anymore than what Tom has given on the Clone Stamp Tool. While not the first tool of choice, it will get the job done and very well I might add, regardless of the uneven background.
 

Archbob

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Hi, I think I'm getting the hang of it. Tom, how did you enhance the coloration of the photo like that afterwards? Auto contrast?
 

Tom Mann

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Something as simple as auto-contrast will never give you results like the version I posted. Unfortunately, I didn't save the PSD file for my tweaked version, but as I recall, once I minimized the water/oil smears, I first developed separate masks for the whole sky, the blue part of the sky, the clouds, and the ground.

I like to get things done fast, so, for a little freebie demo like this, I wasn't about to spend time demonstrating that I could do everything needed using only Photoshop's native tools. Instead, I used a number of plugins. As I recall, I used Topaz Adjust and Nik Color Efx pro's Tonal contrast on everything except the blue part of the sky. I then used Topaz deJPG and Topaz deNoise on the blue part of the sky. I think I finished up by using a Hue / saturation adjustment layer, separately adjusting the saturation of the various colors, and then down-rez'ed it (with a trace of sharpening) to < 700px wide, so that it would display in the forum without any further compression.

It takes longer to write up the procedure than it does to actually do it, so I might have forgotten something. If I think of anything else I did, I'll post it.

Cheers,

Tom M

PS - Oh, I thought of one more thing already: I started by quickly rotating the image a bit to improve the tilted horizon.
 
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Archbob

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Unfortunately I do not have the tools you mentioned. I just have Photoshop CS3 and Photomatix. I may upgrade to the monthly subscription thing with photoshop(since I already have the flash subscription). This is the best I could do with auto contrast, color, and ,levels, plus the curves. Editing seems to be just as important as taking the photo these days as all of the really incredible awesome landscape images these days seem edited. The black marks aren't totally removed, I still have to work on it. On low opacity(I did 15%, what method did you use?) Dissolve for clone stamp?

final1.jpg
 

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Tom Mann

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Sorry ... If I had known that you were interested in both the removal of the water spots, as well as other tweaks to your image, I wouldn't have used the 3rd party tools, and only used PS's native tools in my earlier posting.

So, here are two more native PS techniques that help processing landscape images like this:

a) Bring your starting image into Photoshop through ACR (Adobe Camera Raw), not just straight into Photoshop. ACR is usually thought of only for RAW data files. If your camera puts out RAW files, DEFINITELY use them for post processing, not the JPGs. If your camera only puts out JPGs, ACR is still useful. For example I took the version of the image that u just posted, ran it through ACR, upped the "clarity" control, and played with the tone controls (ie, whites, highlights, shadows, black sliders) to give myself more room for expanding the contrast during further processing.

b) A technique called "large radius unsharp masking" (aka, large-R USM) often adds a nice sense of depth to the ground and clouds. You don't want to add it to the sky because it will exaggerate any imperfections in what should be featureless blue sky. So, after I ran your last image through ACR, I moved it into PS, and developed a mask that excluded the sky. I then applied USM (filter / sharpen / USM) with a radius of around 100 px, at about 10% strength, threshold = 0. I also darkened the sky slightly to increase the drama.

Here is the result. Other than fixing the remaining water smears in the sky, it's starting to look very, very close to the version I posted yesterday, but we've only used tools native to Photoshop.

HTH,

Tom M
 

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Archbob

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Is ACR free or is it something in photoshop?
I generally only have my camera spit out JPGs because of the file size that RAW takes up. I can't fit that many onto my memory stick when I'm out taking photos.

The original image I posted actually already went through some post-processing, its an HDR image.

Right now I'm still trying to remove the water stains. Now that I'm home, I can watch the youtube tutorials.

Also, to try to duplicate your results, I used the Filter-->High Pass tool in CS3.
 
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Tom Mann

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re ACR: It's been part of PS for at least 5 to 10 years. Google it: {adobe camera raw tutorial}

re Saving memory by shooting only JPGs: Forgo a couple of cups of coffee at Starbucks and buy yourself a nice big memory stick. The increase in flexibility and quality of post processing starting with RAW files makes this an absolute no-brainer.

re HPF: Although you might be able to get close to the effect I got using USM, the results will be different. Why not use USM?

Gotta run ...

Tom M
 

Archbob

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I'm actually looking up USM right now. High Pass is much easier to do since you just create a duplicate layer using ctr+j, choose overlay, and then use the filter. I'm pretty new to photoshopping, I mainly used it for the auto contrast and color stuff before so its going to take me a while to learn how to really enhance images.

By the ways for anyone who is reading this for removing the dark water stain spots, patch is much easier to use than clone stamp for most instances.
 

IamSam

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By the ways for anyone who is reading this for removing the dark water stain spots, patch is much easier to use than clone stamp for most instances.

Do you mind uploading an example of your image in which you used patch to remove the dark water spots?
 

Archbob

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Sure, here the image using patch. You can do it with clone stamp as well as many have said here. But I find patch to be smoother and easier for most cases.final1.jpg

I'm really appreciative of this discussion and I'm hoping to learn a lot more here while reading tutorials and watching videos. I want to take my casual photography up a notch.
 
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IamSam

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Hey Archbob.

I think your doing a great job, there's a moderate learning curve involved here.

I see a heavy yellow green tint that's really evident in the clouds just above the horizon and the road itself.

While I realize your in the learning phase, your Patch Tool work is very splotchy.

This is the original. The sky is nice and even toned.....
Screen Shot 2015-08-21 at 8.28.45 AM.png

This is your latest version after your Patch Tool work.
Screen Shot 2015-08-21 at 8.29.14 AM.png

As I have said before, careful Clone Stamp Tool work produces much better results. The trick to the CST is to zoom in very close, lower your settings, flow down to 10% and your opacity down to as low as 20% to 35%, a nice soft brush and most importantly, sample often and close to and in line with the area your working on. The quick fix tools are no substitute for careful work with the proper tool.

Remember, your not just limited to one tool for any given job, you need to learn to use any and all tools it takes to get the desired results. Combine your tools.

Keep up the great work.
 
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