Use Lightroom's Dehaze Tool to Locate Dust Spots

[pegelli]

Yes many methods. I have been using dehaze to find spots for the past weeks. Works quite well except for one thing. After using dehaze LR becomes quite slow to respond to various tools. I tend to jack up the dehaze to get a feel for where the problems are then zero it.

I have found several slightly odd uses for dehaze actually.

I agree Martin, you need to zero dehaze before many other operations, and really apply it for its intended purpose (dehazing) as the last step before export or printing. Especially setting the colour temperature becomes grindingly slow, even with minimal dehaze amounts.

What other "odd" uses have you found? I'd be interested in those as well.

[Bart_van_der_Wolf]

ICE is very dated, and relatively limited technology. You wouldn't need to redo it if you were using up-to-date software such as iSRD in SilverFast. One of the reasons why Epson bundles SilverFast with a number of their scanner models.

And to add for completeness, VueScan also does a fine job on IR detection/removal of dust and scratches on filmscans.

It also supports other scanners with an IR channel, not only Epson, supports over 2500 scanners in total, and the Pro version offers free unlimited upgrades (so purchase once, never have to pay again for the latest version supporting any of the latest scanners). I have been using it on all my scanners over the years, since I purchased a license a little over 14 years ago, and have been upgrading for free since. Some of the best spent money ever, since the quality of the scans (which is very well tweakable) is very good.

As for using DeHaze to detect spots, it looks like a creative use for the tool but, as has been reported by users, it will slow down image updates for anything that happens earlier in the hardcoded sequence of parametric events. I'm not sure if it's more effective that cranking up the clarity or other local contrast adjustments (which are applied much later in the pipeline, and thus should be fast).

I think that LRs Dust visualisation tool is pretty neat, when you concentrate on the circular ring patterns. On filmscans it might get confused by some grain or dye-clouds that seem to clump together in the 3D projection of the emulsion on a flat plane. So I prefer the IR cleaning if possible (i.e. on chromogenic  film, so without silver or silver-residue in improperly processed film like sometimes happened with Kodachromes). The IR approach also removes scratches, which stand out by having a different IR signature due to a different refraction angle in addition to a density difference with visible light.

Cheers,
Bart

[john beardsworth]

Sometimes a picture tells more then a thousand words, why argue?

For a fair comparison you need more than one "official" image to reflect how the the visualisation slider affects the image detail, and you can change its value without the performance impact both you and Martin have observed. The clarity method is also less effective than it used to be - IIRC it used to top out at 400%.

[pegelli]

For a fair comparison you need more than one "official" image to reflect how the the visualisation slider affects the image detail, and you can change its value without the performance impact both you and Martin have observed.

You're right, feel free to add other and/or better examples 

[Martin Kristiansen]

I agree Martin, you need to zero dehaze before many other operations, and really apply it for its intended purpose (dehazing) as the last step before export or printing. Especially setting the colour temperature becomes grindingly slow, even with minimal dehaze amounts.

What other "odd" uses have you found? I'd be interested in those as well.

OK. But this is really obscure. I recently shot a number of rock art images painted by the Natal Bushman. Dating has shown some of these paintings are 3500 years old so some of them are quite faded and or dust covered.  Over the years I have found a number of ways to make these images visible but none as quick and easy as dehaze.

I am a commercial photographer and do a lot of product catalogue photography. Dehaze helps a lot with glassware where colour saturation isn't so important as I usually heavily desaturated these images anyway. Also works well when shooting items behind plastic that I may not be permitted to remove. Obviously for this I use dehaze selectively by visiting photoshop.

Not sure about this but I suspect dehaze will be a big help with underwater photography. It sure helps shooting koi fish in a pond.

Dehaze helped a lot with an image I shot in Tibet with light streaming into a monastery. Really popped the light beam. Also used selectively.

Dehaze strengthens faint rainbows very successfully.  I was converting this particular image to B/W and the rainbow is hard to make at all visible. I did mange using other tools in the past but gave it a try with dehaze. Much easier.

Obviously there are other ways to do all these things but sometimes a tool makes something easier and that's still a valid use.

Pretty sure I have forgotten something else. I sat for about 4 hours when I first looked at the tool and played with a wide range of images to get an idea how else it could help me.

Oh yes. To replicate shooting through glass move the slider to the left. Then apply it through a layer mask with a gradient on it.

[Peter McLennan]

I have found several slightly odd uses for dehaze actually.

Me, too.  Among the first things I did was experiment with combining max dehaze and min clarity and vice versa.

Looks like Bret wins the voodo/placebo wars.  Thanks, Bret.

[john beardsworth]

Looks like Bret wins the voodo/placebo wars.  Thanks, Bret.

No wars, Peter, just Bret throwing abuse. And his post was about using it to find dust spots, not whether it's useful as a general effect, which it obviously is.

[kirkt]

Just slide the Black Point on the Tone Curve up to a point about halfway between the midtown point and the highlight point and boost clarity to 100.  As a bonus you get to see all of the banding noise in the red channel of the Canon sensor!

You can make a preset to do this temporary edit.

Or do it however you want.

kirk

[Bart_van_der_Wolf]

Just slide the Black Point on the Tone Curve up to a point about halfway between the midtown point and the highlight point and boost clarity to 100.  As a bonus you get to see all of the banding noise in the red channel of the Canon sensor!

You can make a preset to do this temporary edit.

Hi Kirk,

And how does the dust visualisation tools show the dust?

IMHO, the benefit of the dust visualisation tool is that it also works in shadows and in other parts of the scene, not only in smooth skies. We humans are pretty good at recognizing patterns, and a ring is easy to spot, as is often an odd shape that doesn't look like it's part of the scene.
It also doesn't create entries in the editing history list.

Cheers,
Bart

[Mike Sellers]

Thanks for the tip Bret
Mike

[kirkt]

Hi Bart,

Based on this screenshot of the same area in the above example, I'd say pretty poorly.  Maybe there is a way to control this tool and its sensitivity, but I don't use LR enough to know.

Maybe the Adobe engineers developed the algorithm so that, if the visualization tool does not accentuate it, it is not worth addressing.

kirk

[john beardsworth]

Based on this screenshot of the same area in the above example, I'd say pretty poorly.  Maybe there is a way to control this tool and its sensitivity, but I don't use LR enough to know.

As I pointed out before, you use the tool's slider. Depending on the image area's detail, it can quickly reveal more spots. Set the tool's option to Auto too, so you can hide the healing pins by moving the cursor in and out of the image, and use the A shortcut to quickly toggle the visualisation mask and judge your work based on the image's intended image appearance (rather than on its appearance after being crappified by Dehaze or another method).

[digitaldog]

I just tested quickly using A key mask versus Dehaze at 100 and vastly prefer the later. I can see what I'm spotting and the toggle on and off with the A key is slow on this end.

[pegelli]

As I pointed out before, you use the tool's slider.

Which slider is that? None of the 3 sliders in the spot removal tool window have any effect on the mask.

EDIT: found it, it's at the bottom of the screen below the picture.

[Wayne Fox]

I just tested quickly using A key mask versus Dehaze at 100 and vastly prefer the later. I can see what I'm spotting and the toggle on and off with the A key is slow on this end.

I agree with this, I really like seeing the image, even if it is pretty strange instead of the weird mask offered by the visualize tool.  Sometimes in skies with weird cloud formations, I get false indications of spots, so I am constantly toggling visualization with the A key, using deHaze works quite well.

However, on my IQ180 files there is definitely a performance hit.  For just spots it’s pretty minor, noticeably longer but not annoyingly so. But if I need to click and drag, the lag is extreme, to the point as making it unusable.  But pretty easy to use a combination of the two when cleaning things up.

[kirkt]

Here is the same area from the previous, with the dust spot slider set to something that shows spots and does not show noise (about 85-90% of full slider).  If you don't mind having to toggle back and forth to see your spots and then check the auto-heal, then have at it.  Seems like a lot of hassle compared to just healing on the color image with contrast added, however you choose to add the contrast.  Also, for my test, it is a lot easier to see the spots (and fewer false-positives) in boosted-contrast color (when compared to the visualization tool) when zoomed to fit the width of the image, or anything other than 1:1.

kirk

[john beardsworth]

 Seems like a lot of hassle compared to just healing on the color image with contrast added

It isn't a hassle at all, it's just pressing the A button on the keyboard and saving the effort of reversing out whatever contrast damage you've done. But if that's the way for you, why not treat yourself to "The SLR Lounge Lightroom 4 & 5 Presets System’s Advanced Dust Correction System" preset bundle - a true bargain at just $149....

[David Sutton]

Or use Nik Tonal Contrast over a clone layer in PS and have no buttons to push.

[Martin Kristiansen]

While on the subject PS heal tool and spot heal tool are vastly improved. 

[kirkt]

It isn't a hassle at all, it's just pressing the A button on the keyboard and saving the effort of reversing out whatever contrast damage you've done. But if that's the way for you, why not treat yourself to "The SLR Lounge Lightroom 4 & 5 Presets System’s Advanced Dust Correction System" preset bundle - a true bargain at just $149....

What contrast damage?  Just reset the temporary tone curve when you are finished your spot healing and get on with the edit. 

kirk