Any way to remove hot pixels automatically in PP?

Started Jul 16, 2013 | Discussions thread
Mark K W
Senior MemberPosts: 1,060
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Re: Any way to remove hot pixels automatically in PP?
In reply to stern, Jul 17, 2013

stern wrote:

Hi,

Tried some long(ish) exposures in winter (30 sec., F13). Outside temperatures were very low (damn cold...), nevertheless the sensor of my Pentax K7D obviously became warm anyway, so I ended up with hundreds of red, blue and green dots on my pictures taken in jpg format. I am wondering if there is any automatic tool for Mac that does the trick in removing them in one go. I haven't used Lightroom yet, but have read in forums that LR might remove hot pixels automatically after importing (though this might only apply for RAWs).

Yes, it is my understanding that LR (and ACR) do run a hot-pixel algorithm on importing RAWs. That is part of the Bayer de-mosaicing RAW front end, so is before you, the user, apply the overall image NR. It is different and very local algorithm within the RAW filter decoding to locate and remove them as opposed to the generic noise-reduction algorithm which is after RAW decoding. The hot-pixel removal is direct and only to each hot-pixel, whereas NR is applied to the whole image (or areas selected with LR's adjustment brush).

I think most RAW processors do the same.

Not sure there is any simple way to remove them from JPEGs (other than as stated by using LE NR setting on your camera to remove them in-camera before the JPEG is made; you can also set the sharpness to low in the camera to help reduce them).

Now that you have them baked in your JPEGs, you can try NR or even a 1-pix blur, but you will lose overall image quality and sharpness with both those methods - although you can apply them locally with masking so e.g. do them heavily in dark sky areas, and less in areas where the image already contains bright detail.

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