this oughta be good. pulling up a chair… ready to take some notes! 🙂
oh yea, bump. 🙂
If you’ll get me a chair, I’ll get us both some fresh coffee. 🙂
Method for Removing Halos
Excommunication?
John, too much beer in the Hofbräuhaus ?
Joking apart – by PAINTING one could easily get rid
of the halos. And where is the solution by PhS ?
G.H.
I’d probably use a brush about the same width as the halo, set the blend mode to Darken, and very carefully paint over it. That’s tedious and prone to hand-shake, of course. You might also be able to isolate it in one of the channels, depending on the image, make a selection from it, and then adjust it with the usual tools or possibly even Match Color to the surrounding area.
Yes – that’s painting. I was wondering whether we had a
solution like this: find the contours (edge filter as LIGHT lines) and subtract the lightness of the contours (partly) from the original image, automized with user interaction by defining a blend factor.
The disturbing halos are always lighter. If there should be dark halos then they are less annoying.
Best regards –Gernot Hoffmann
Gernot, have you got an image with a halo you want removing?
I have an idea that might work.
Careful, Deebs.
Gernot is a REAL engineer, and he gets a little testy with the Off-Topic stuff.
Doc Hoffmann:
It makes perfect sense to do a "Find Edges" on a copy of the haloed image, create a selection from the result, perhaps expand and/or blur that selection in an Alpha channel and work from selection made from the manipulated Alpha channel. Obviously, the amount of selection expansion is going to be predicated by the resolution of your image.
There’s a tutorial about this somewhere…that’s how I learned about this many moons ago.
That’s pretty much along the lines of what I was thinking.
Oh well 🙁
A test image is here (200kB):
<
http://www.fho-emden.de/~hoffmann/halotest.jpg>
That’s me.
The purpose of this investigation: older cameras
like Minolta RD-175 (about 1998) create clearly
visible halos at all contours.
Newer cameras like Nikon D100 create halos only
for strong contour contrasts.
That means – the problem is NOT solved by modern
technology. It’s only camouflaged.
Therefore I’m using this OLD technology in order
to find methods how to improve NEW technology
images.
Best regards –Gernot Hoffmann
It’s good to finally put a face to the name.
What I’m seeing in the image you posted is one that is just a wee bit out of focus to begin with.
Now…you say that’s a TEST image. Does this mean that it’s straight out of the camera, as-is? Have you done ANYTHING to itincluding further JPEG compression?
If so, could you post a link to a big, untouched file? Go ahead, I can take it. I’ve got a fast cable connection.
🙂
getnot, you look like mr. einstien! 🙂 cheers!
Another way is not to create the halos in the first place…
Try this
Duplicate image, flatten duplicate.
On flattened duplicate:Duplicate background layer, Go to Filter>Other>High Pass apply the high pass filter until you just see a thin area of white around edges of your object or you see the edges of your object showing through the 50% gray overlay. Click ok.
Change the High pass layer’s blending mode to Overlay (lots of sharpening and brightening of the overall image) or to Soft Light (less sharpening and brightening) Use the opacity sliders on the Layers palette to decrease or fade the effect….
One of the best methods out there!!!
" Another way is not to create the halos in the first place…"
I think the point that Gernot’s making is that the images have haloing straight away, right out of the camera.
ooops….
Another way would be to create a mask using "glowing edges" on a duplicate layer instead of find edges…lots more control over the mask, more blurring options using edge width, brightness and smoothness…convert the "glow" to grayscale using desaturate and clean up the "mask" with the dodge and burn tools…
You can also do this on a duplicate channel for more control…
I’ve been playing around with it but am not satisfied yet.
Bis später…
Gernot:
Try this…
Duplicate layer
Glowing edges Edge width between 1 and 2, low brightness, low softening values… Desatuate
Use dodge tool set to highlights at 50% to add to white edges Use burn tool set to shadows at 50% to remove grey edges and improve black areas (may take a couple of passes with either tool)
Select all
Go to Channels palette and click make selection from channel then click make channel from selection.
Use the Minimum filter to increase diameter of "white edges" Blur 2-3 pixels using gaussian blur
Create selection from alpha channel
Create a second duplicate layer from layers palette
Use this layer with the selection from alpha channel to create a 2-3 pixel blur. Change the duplicate layer’s blending mode to darken or soft light, reduce opacity of duplicate layer until halos are gone
A little glowing thingy that fits either comfortably or uncomfortably around your head…
It’s how we "fake sharpening" in Photoshop. What happens is Photoshop’s USM and other sharpening methods use a small line of white pixels around an edge of an object to increase constrast and to make your eye "see" the object as being sharper…
The Egyptians are credited with coming up with the technique to make hieroglyphics look sharper….
Thanks to everybody for the suggestions. I’ll be going to check the methods by and by.
The halos are inherent to all photos by Minolta RD-175.
The technology is from 1995 and the camera itself from 1997. The camera uses a beam splitter and three filtered CCD arays with 380.000 pixels each (opposed to the Bayer matrix system, which requires demosaicing). Raw data roughly 1MB per image. The final converted result is 1528 x 1146 pixels (1.75 Mp). This image is extrapolated by factor two from the sensor data. 764 x 573(0.438 Mp). The factor is not exactly two but near to. The somewhat unsharp look (as mentioned by Phosphor)is IMO as well caused by the digital system. The zoom lens AF 24-85 are probably very good.
Altogether this camera was a rather progressive design.
A removable harddisk with 130 MB for 112 uncompressed images !
Best regards –Gernot Hoffmann
I only saw this post now. I´ve recently dug into methods of perfecting very detailed masks for blending several RAW develops of the same file into a more compressed dynamic range.
Anyway, here´s a few tips for removing halos (from sharpening, and from imperfect masking).
1) Use the Blur Tool at low opacity, set the tool to Darken or Lighten.
or
2) Use a dodge & burn overlay layer;
Alt-click Create New Layer icon on Layer Palette; Mode: Overlay, Fill with overlay-neutral Color checked.
Zoom in close on a halo. Pick a small paintbrush and paint with 30% black over a halo (white or black). Dont worry about accuracy.
Right-click this new layer and choose Blending Options. Adjust Black (or white) Point slider for ‘Underlying Layer’ to restrict effect to the halo boundaries. Then Alt-drag the black point slider a bit to blend in the effect more smoothly.
Thats it, now casually paint over the rest of the halos. Try it, it works.
Mathias
Here´s my result just using the Blur Tool with Darken blend mode @ 18% opacity on a duplicate layer (its painted, I admit it)
<
http://www.pixentral.com/show.php?pic=15iGKbW5RZ5eezGJASMV0Z 7Ya1lM2k0>
Note that with this method, you must resharpen.
If you are looking for an automated way, Perhaps one could couple a duplicate, blurred layer in darken mode with Advanced Layer Blending as described above.
Mat
Mathias,
thanks – looks already like an improvement.
I’ll have to test all suggested methods, which will
take some time.
By the way: the halos as in my original image create
somewhat sharper edges on a laser printer, e.g. by
printing by 5" x 4"" – not really bad.
This ‘original image’ is a reproduction of the Minolta
image with perspective rectification (my own image proces- sing system). This doesn’t remove or enhance the halos.
Based on the experiences by RD-175 I had bought some years ago a digital camera which creates images with minimal halos. At this time it was Nikon D100 – not merely MANY pixels but good pixels.
Best regards –Gernot Hoffmann
Btw, Gernot, you may want to remove the halos before applying lens corrections, as it works best when the halos are the same width (Gaussian).
Mat
Mathias,
thanks for your contributions. I’ll check everything later. At least I’m now sure that halos can be eliminated or reduced automatically.
The underlying idea: should I really put a US$ 4500 camera + flash into the garbage bin ? No, I can still use it at home instead of a Polaroid camera (for documenting my wife’s progress as an artist).
Best regards –Gernot Hoffmann
Regarding
Therefore I’m using this OLD technology in order to find methods how to improve NEW technology
images.
One word: RAW. Dont apply in-camera sharpening, but do it yourself in RAW or Photoshop.
I’m not really familiar with all the layer blending tricks. Furtheron I think, the action shouldn’t depend on too many arbitrary tweaking parameters.
The solution is now:
Make copy
Find edges (no parameters)
Reduce Brightness full left
Reduce Brightness full left (again)
Subtract this black image (with slightly colored gray-ish contours) from the source image
The result:
Smaller halos but increased sharpness.
I’m considering this as an improvement (of course it’s not a good image, judged by the state of the art).
Low-compression JPEG, about 220kBytes. Please use Actual Pixel View (screenshot with menues):
<
http://www.fho-emden.de/~hoffmann/halotest2.jpg>
Thanks again for all suggestions (also to Christine, here it’s my impression that the glowing edges are somewhat off the contour centerlines).
Best regards –Gernot Hoffmann
