Contrast Mask & Gaussian Blur

jm-net

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I have used very often the contrast mask method to improve the resolution of dark and bright areas in my pictures. I'am very satisfied with this method - with one exception:

Between areas with high luminescence differences there are very ugly halos (see attached example file). As far as I can analyse it, the reason is the behavior of the Gaussian Blur Filter, which is the essential tool for this technique. This filter delivers in the center of dark or bright areas an equally distributed mask surface. But near to borders to inverse areas the filter produces gradients which are causing the halos.

Is there an alternative filter or technique, to blur dark and bright areas homogenous all over their range?

Regards
Joachim

 
how much blur are you applying?

to prevent those haloes (and still get excellent contrast masking) you need to use a very substantial blur
enough so that all detail is completely obliterated from the desat layer
should be just short of turning the mask into nothing but grey globs
("nothing but grey globs" is the title of my upcoming novel)
on images from my 6 mpx camera i often use a g blur of 50-80

feivel
I have used very often the contrast mask method to improve the
resolution of dark and bright areas in my pictures. I'am very
satisfied with this method - with one exception:

Between areas with high luminescence differences there are very
ugly halos (see attached example file). As far as I can analyse it,
the reason is the behavior of the Gaussian Blur Filter, which is
the essential tool for this technique. This filter delivers in the
center of dark or bright areas an equally distributed mask surface.
But near to borders to inverse areas the filter produces gradients
which are causing the halos.

Is there an alternative filter or technique, to blur dark and
bright areas homogenous all over their range?

Regards
Joachim

 
Thank you for your hint. I used 40 pixel, because a value between 20 and 60 was recommended in literature.

Applying 80 pixel - as you suggested -, I got a better result. But there is still a small halo and the enhancement to 80 caused a visible worse contrast as achieved with 40.

After my experiments I have the opinion, that the gradient of the gaussian blur near the borders is the reason. To achieve sharp borders between blured bright and dark areas, I tried to select the areas of comparable luminescense with the magic wand to blur them seperately and to do the same with the inverted selection. In principle this technique worked, but it is cumbersome and impossible to be automated. I believe the best way would be an improved Gaussian Blur to achieve homogeneous bluring all over the areas of equal luminescence - but I didn't find such a tool yet.

Regards
Joachim

.
feivel
I have used very often the contrast mask method to improve the
resolution of dark and bright areas in my pictures. I'am very
satisfied with this method - with one exception:

Between areas with high luminescence differences there are very
ugly halos (see attached example file). As far as I can analyse it,
the reason is the behavior of the Gaussian Blur Filter, which is
the essential tool for this technique. This filter delivers in the
center of dark or bright areas an equally distributed mask surface.
But near to borders to inverse areas the filter produces gradients
which are causing the halos.

Is there an alternative filter or technique, to blur dark and
bright areas homogenous all over their range?

Regards
Joachim

 
Applying 80 pixel - as you suggested -, I got a better result. But
there is still a small halo and the enhancement to 80 caused a
visible worse contrast as achieved with 40.

After my experiments I have the opinion, that the gradient of the
gaussian blur near the borders is the reason. To achieve sharp
borders between blured bright and dark areas, I tried to select the
areas of comparable luminescense with the magic wand to blur them
seperately and to do the same with the inverted selection. In
principle this technique worked, but it is cumbersome and
impossible to be automated. I believe the best way would be an
improved Gaussian Blur to achieve homogeneous bluring all over the
areas of equal luminescence - but I didn't find such a tool yet.

Regards
Joachim

.
feivel
I have used very often the contrast mask method to improve the
resolution of dark and bright areas in my pictures. I'am very
satisfied with this method - with one exception:

Between areas with high luminescence differences there are very
ugly halos (see attached example file). As far as I can analyse it,
the reason is the behavior of the Gaussian Blur Filter, which is
the essential tool for this technique. This filter delivers in the
center of dark or bright areas an equally distributed mask surface.
But near to borders to inverse areas the filter produces gradients
which are causing the halos.

Is there an alternative filter or technique, to blur dark and
bright areas homogenous all over their range?

Regards
Joachim

 
That's what it's called in PSP8...I'm sure something similar exists in PS.

Edge preserving smooth set to maximum will significantly blur all the information other than the edges between contrast areas. With a small done of gaussian over the top to finish it off, it should provide great contrast blending while still leaving the sharp division between light and dark areas.

--
Justin
 
I believe the best way would be an
improved Gaussian Blur to achieve homogeneous bluring all over the
areas of equal luminescence - but I didn't find such a tool yet.
Burring areas of equal luminosity doesn't cause any change. For instance, if you create a 50% gray circle on a white background, and use the Lasso tool to select a part of the interior of the circle and blur the selection, the blurred area will be indistinguishable from the rest of the circle. Blurring only has an effect at the transition point between two different luminosities, i.e. the edge of the circle. Blurring causes the sharp transitions between differing luminosities to fade gradually into each other. You can see that in the circle example by blurring the whole image instead of just the selection.

If you want the affects of the luminosity mask to have sharp edges--don't use blurring at all. Also, you certainly aren't limited to the rudimentary luminosity mask made by inverting your image. You can use a variety of methods to adjust the luminosity mask. I prefer a Gradient Map adjustment layers, which are explained here:

http://retouchpro.com/tutorials/?m=show&id=132
Regards
Joachim

.
feivel
I have used very often the contrast mask method to improve the
resolution of dark and bright areas in my pictures. I'am very
satisfied with this method - with one exception:

Between areas with high luminescence differences there are very
ugly halos (see attached example file). As far as I can analyse it,
the reason is the behavior of the Gaussian Blur Filter, which is
the essential tool for this technique. This filter delivers in the
center of dark or bright areas an equally distributed mask surface.
But near to borders to inverse areas the filter produces gradients
which are causing the halos.

Is there an alternative filter or technique, to blur dark and
bright areas homogenous all over their range?

Regards
Joachim

 
Have you tried creating a layer mask on the contrast mask layer and lighlty masking any halos that show up?

jbf
I have used very often the contrast mask method to improve the
resolution of dark and bright areas in my pictures. I'am very
satisfied with this method - with one exception:

Between areas with high luminescence differences there are very
ugly halos (see attached example file). As far as I can analyse it,
the reason is the behavior of the Gaussian Blur Filter, which is
the essential tool for this technique. This filter delivers in the
center of dark or bright areas an equally distributed mask surface.
But near to borders to inverse areas the filter produces gradients
which are causing the halos.

Is there an alternative filter or technique, to blur dark and
bright areas homogenous all over their range?

Regards
Joachim

 
It's Smart Blur in Photoshop. Good idea.

Steve B.
That's what it's called in PSP8...I'm sure something similar exists
in PS.

Edge preserving smooth set to maximum will significantly blur all
the information other than the edges between contrast areas. With
a small done of gaussian over the top to finish it off, it should
provide great contrast blending while still leaving the sharp
division between light and dark areas.

--
Justin
 
Mr. Zackiedawg (unusual - German name ..?),

Thanks for the 'Edge Preserving Smooth' tip which worked wonders. You suggested "a small done of gaussian over the top to finish it off" Wouldn't gaussian blur after that soften the details throughout the image?

"I'm sure something similar exists in PS", Dunno, unless it's with CS.

I mainly use PSv6 and Elements2. By the way Nothing in PSPv8 'matches 'the "Transform / skew / distort / perspective" control in Elements2, which feature is also lacking in PSv6. Maybe it's in PSv7 or CS again dunno.

I cut my teeth on PSP since it first came out. Loved it and always loyal. Then a few years ago veered toward PS without not enough money to get CS.

About a year ago I upgraded to PSP v 8 which I hardly use now, mainly because I'm unfamiliar with it.

G
That's what it's called in PSP8...I'm sure something similar exists
in PS.

Edge preserving smooth set to maximum will significantly blur all
the information other than the edges between contrast areas. With
a small done of gaussian over the top to finish it off, it should
provide great contrast blending while still leaving the sharp
division between light and dark areas.

--
Justin
--
me :
http://www.pbase.com/image/27464432
Roscoff
http://www.pbase.com/geo_paris_fr/roscoff21072002
 
PSP8 has got Geometric correction controls for horizontal and vertical perspective and skew. It's also got lens correction controls for barrel, pincushion and fisheye. I've never found it wanting, so what does Elements do extra?
I mainly use PSv6 and Elements2. By the way Nothing in PSPv8
'matches 'the "Transform / skew / distort / perspective" control in
Elements2, which feature is also lacking in PSv6. Maybe it's in
PSv7 or CS again dunno.
--
C75OUZ
 
Glad to hear it worked. I don't have any photoshop programs, so I have learned alot with psp8.1 since I've had it.

I thought the small amount of Gaussian after might give just a bit more smoothing than Edge preserving could give, but keeping it low at 2 or 3 would still preserve the contrast borders. Though full edge-preserving smooth should produce enough blur within the non contrast areas to produce the effect without needing it.

My screenname isn't German...it was created and named after my dog, Zack, a black Labrador Retriever who passed away a couple of years ago at 14 years old. I had created the name when he was around, and didn't want to give it up when he passed, so it has stuck with me (it is also my AOL screenname).

My actual name is Justin...and I am 6/8 Irish, 1/8 Dutch, and 1/8 American Indian...born in England, currently living in Florida.

PSP is doing a pretty good job at keeping up with PS for a great price. There are still a few things they are missing, and a few things they actually do a little better. For the money, I find PSP to be an excellent and fairly advanced post processor.

--
Justin
 
PSPv8 has more controls and tools than Elements2, but I feel more at home with Elements2 and PS.

In response to your Q :

I am to a limited extent familiar with PSP geometric H and V skew controls. I've used this feature only a few times. This feature gives you two windows and you must type-in the + or - % desired.

Whereas Elements frames image with eight points and using skew and distortion controls you can 'mouse-pull' or 'mouse-slide' those points (even with points outside image) to tilt separate sides of the image the way you want.

What's lacking in Elements compared to PSv6 is that Elements does not display or accept ANY images in 16 bit tiff colour depth. However, Elements supports colour depth of 8 bit TIFF images. Elements has no channel display feature. PSP has channels as does of course PSv6.

otoh Both PSv6 and PSPv8 support the colour depth of 16 bit Tiff images. Even better, WITH 16 bit TIFF images PSPv8 is less limited than PSv6 because it allows working in layers. BUT even PSv6 does not allow layers with 16 bit Tiff images. Maybe later versions do. otoh PSv6 allows layers with 8 bit Tiff images.

However, PSv6 allows working with channels with 16 bit TIFF images.

G
I mainly use PSv6 and Elements2. By the way Nothing in PSPv8
'matches 'the "Transform / skew / distort / perspective" control in
Elements2, which feature is also lacking in PSv6. Maybe it's in
PSv7 or CS again dunno.
--
C75OUZ
 
Elements has no channel display feature. PSP has channels as does
of course PSv6.
If you know what a channel is, you can create them in PSE2.
otoh Both PSv6 and PSPv8 support the colour depth of 16 bit Tiff
images. Even better, WITH 16 bit TIFF images PSPv8 is less limited
than PSv6 because it allows working in layers. BUT even PSv6 does
not allow layers with 16 bit Tiff images. Maybe later versions do.
otoh PSv6 allows layers with 8 bit Tiff images.

However, PSv6 allows working with channels with 16 bit TIFF images.

G
I mainly use PSv6 and Elements2. By the way Nothing in PSPv8
'matches 'the "Transform / skew / distort / perspective" control in
Elements2, which feature is also lacking in PSv6. Maybe it's in
PSv7 or CS again dunno.
--
C75OUZ
 
Thank you much for your comment. btw I looked at
http://retouchpro.com/tutorials/?m=show&id=132

If you are the author of the site, Then my compliments. Sliding/opening menu on the left. First time I've seen that. The content of the tutorial is brilliant.
If you know what a channel is, you can create them in PSE2.
Putting it that way I dunno whether I actually 'know' what a channel is. I suppose that this feature in PSv6 and PSPv8 allows the splitting of colours composing an image into three or four gray masks each relating to a single colour found in rgb or cmyk etc. Is that right?

I consider myself not 'very' good in retouching, much less an expert, but perhaps better than the average user of retouching software. I'm no authority. Wish I were.

I do not Q the what you say about "create them" (channels).

I simply notice nothing in the tool bar of PSE2 giving DIRECT access to Image/Mode/Channels as is found in PSv6 or PSPV8.

I looked in the index of PSE2 in 'glossary' and found no reference to channels. In PSE2 'contents' I found layers, but not channels.
Elements has no channel display feature. PSP has channels as does
of course PSv6.
If you know what a channel is, you can create them in PSE2.
otoh Both PSv6 and PSPv8 support the colour depth of 16 bit Tiff
images. Even better, WITH 16 bit TIFF images PSPv8 is less limited
than PSv6 because it allows working in layers. BUT even PSv6 does
not allow layers with 16 bit Tiff images. Maybe later versions do.
otoh PSv6 allows layers with 8 bit Tiff images.

However, PSv6 allows working with channels with 16 bit TIFF images.

G
I mainly use PSv6 and Elements2. By the way Nothing in PSPv8
'matches 'the "Transform / skew / distort / perspective" control in
Elements2, which feature is also lacking in PSv6. Maybe it's in
PSv7 or CS again dunno.
--
C75OUZ
--
me :
http://www.pbase.com/image/27464432
Roscoff
http://www.pbase.com/geo_paris_fr/roscoff21072002
 
I am to a limited extent familiar with PSP geometric H and V skew
controls. I've used this feature only a few times. This feature
gives you two windows and you must type-in the + or - % desired.

Whereas Elements frames image with eight points and using skew and
distortion controls you can 'mouse-pull' or 'mouse-slide' those
points (even with points outside image) to tilt separate sides of
the image the way you want.
Actually, PSP8 has the grid skew feature as well, and you can choose the number of H & V points you want in your grid. Once the grid is set to the desired number of points, you can drag the points as desired to achieve any amount of skew, perspective, size, or free distort you want.

This feature is one of the 4 tool icons down the left vertical toolbar, where the 'straightening' tool is located.

I do think that PSP8 added pretty much everything anyone ever wished they had from PS Elements and even some of the newer features from PS CS...plus a few of their own unique features.

--
Justin
 
Sorry about my misinterpretation of your name. Now I see the word 'dawg' in your pseudonym. Yr dog Zach - his name is the diminutive of Zacharias variation of Zachariah. Apparently you've got a biblical turn of mind, because Zacharias was the father of John the Baptist. Réf Luke - new testament. btw As for 'Justin', there was a Saint Justin (early Christian martyr born in Samariah ~ 100 AD). That's going back a bit, so I assume no relation or at best a distant one.

I'm impressed by your lineology - born in England yet destined to live out the rest of your existance in Florida. It's as if your 1/8 Amerindian ancestor decided where you'd end up. Hey, man, where's that wigwam ..

I generally agree with all you say about PSP. I regret you've not got PSE2 or PS so that we can explore this subject in greater depth. But find somebody who's got PSE2 and try out what I described.

Anyhow, as you said PSP in the tool bar also offers perspective/straighten features with points which you can pull and slide. And you have a complete control of perspective, skew etc. But, and unless I'm missing something, although you can drag the points which way you want the image 'to go', it's still not a visualisation in real time as with PSE2 where by 'dragging'those points at the same time you're also dragging the image or parts of the image itself.

With PSE2 you can see where got it right the first time.

With PSP once you've dragged the points, it's only after the click that the image adjusts itself to those points which had been dragged. With PSP correcting perspective and skew becomes a more labourious 'start again' process.

I'd say this skew/distortion feature in PSE2 is 'almost' worth the price of the whole package, and it's only in the domain of this application that I find PSE2 to be superior to PSP.

Furthermore, PSP is far less memory demanding than all versions of PS pro and with my limited budget and limited skills if I had to start again for the money I'd choose PSP over PS pro professional versions. Like you I believe that the latest version of PSP runs PS a very close second and for the price there's no equal. However, in addition to PSP8 I've got PS6 and PSE2, so I make do with what I got.

Cheers,
G
PS

Do you know that in FR the lettre 'G' is pronounced 'jay' and the lettre 'J' is pronounced 'gee', so you see my first initial is pronounced 'jay' like your first initial in English! Maybe we're related :)
Glad to hear it worked. I don't have any photoshop programs, so I
have learned alot with psp8.1 since I've had it.

I thought the small amount of Gaussian after might give just a bit
more smoothing than Edge preserving could give, but keeping it low
at 2 or 3 would still preserve the contrast borders. Though full
edge-preserving smooth should produce enough blur within the non
contrast areas to produce the effect without needing it.

My screenname isn't German...it was created and named after my dog,
Zack, a black Labrador Retriever who passed away a couple of years
ago at 14 years old. I had created the name when he was around,
and didn't want to give it up when he passed, so it has stuck with
me (it is also my AOL screenname).

My actual name is Justin...and I am 6/8 Irish, 1/8 Dutch, and 1/8
American Indian...born in England, currently living in Florida.

PSP is doing a pretty good job at keeping up with PS for a great
price. There are still a few things they are missing, and a few
things they actually do a little better. For the money, I find PSP
to be an excellent and fairly advanced post processor.

--
Justin
 
Good post and thanks for the link - I'll try playing around with this, it's something I had no idea how to use before.
I believe the best way would be an
improved Gaussian Blur to achieve homogeneous bluring all over the
areas of equal luminescence - but I didn't find such a tool yet.
Burring areas of equal luminosity doesn't cause any change. For
instance, if you create a 50% gray circle on a white background,
and use the Lasso tool to select a part of the interior of the
circle and blur the selection, the blurred area will be
indistinguishable from the rest of the circle. Blurring only has
an effect at the transition point between two different
luminosities, i.e. the edge of the circle. Blurring causes the
sharp transitions between differing luminosities to fade gradually
into each other. You can see that in the circle example by
blurring the whole image instead of just the selection.

If you want the affects of the luminosity mask to have sharp
edges--don't use blurring at all. Also, you certainly aren't
limited to the rudimentary luminosity mask made by inverting your
image. You can use a variety of methods to adjust the luminosity
mask. I prefer a Gradient Map adjustment layers, which are
explained here:

http://retouchpro.com/tutorials/?m=show&id=132
Regards
Joachim

.
feivel
I have used very often the contrast mask method to improve the
resolution of dark and bright areas in my pictures. I'am very
satisfied with this method - with one exception:

Between areas with high luminescence differences there are very
ugly halos (see attached example file). As far as I can analyse it,
the reason is the behavior of the Gaussian Blur Filter, which is
the essential tool for this technique. This filter delivers in the
center of dark or bright areas an equally distributed mask surface.
But near to borders to inverse areas the filter produces gradients
which are causing the halos.

Is there an alternative filter or technique, to blur dark and
bright areas homogenous all over their range?

Regards
Joachim

 
Thanks for the info and comparison of the PSP and PS systems. You are right...in PSP8 when using the distortion grid, in order to see the effect of the drag, you have to click on the checkmark icon, and then Undo if you don't like it. It is nice to have that feature added, but I suppose it would be even better if you could see the changes in real-time.

The naming of the dog was mostly influenced by his parents and lineage: His father was a pure-bred trophy-winning hunter named "Big Zeke" and his mother was a pure-bred show-winning dog named "Zelilah". So a name in the "Z"s seemed appropriate, and Zachary (Zack for short) seemed like a good one.

As for Saint Justin, my mother and father were raised Catholic (though no longer practicing) and I am generally non-religious myself, but any names they chose had to be approved by my Catholic grandmother...so a saintly name was a must. My mother wanted to be able to name me after a non-religious figure who happened to have a Catholic name. She loved the adopted name of a 60s fashion photographer and manager, Justin de Villeneuve (real name Nigel Davies), and recalled that there was a Roman emperor named Justinian...so once she researched and discovered there was indeed a saint with that name, she picked it for me and my grandmother approved (born in 1968, I am the child of hippies!).
I'm impressed by your lineology - born in England yet destined to
live out the rest of your existance in Florida. It's as if your 1/8
Amerindian ancestor decided where you'd end up. Hey, man, where's
that wigwam ..
Yep...my mother is the American indian - she and my father decided to move to the US in 1970 with me in tow, where we lived in New Jersey, California, and finally Florida. I went to college in New Orleans Louisiana, then moved back to California after college, until 1994 when the big earthquake crushed my home and chased me back to Florida where I still had some family. Been here since, but no wigwam. My tribe was originally from the New Jersey area, but were exiled to Oklahoma where they currently reside.

--
Justin
 
Thanks for those nomenclature explanations. Yours a fascinating family history. Your crushed house and when you were small all that moving to begin again. Goodness musta a been difficult for you as a kid as well as an adult. I hope things are better for you.

"my mother and father were raised Catholic" I'm not catholic, but many Indians were converted.

btw here are some interesting site regarding your mom's NJ indian origines.

Should you make it across the 'big water', I'm good for a coffee and even a modest meal.

New Jersey Indians - The Nanticote tribes
http://www.jersey.net/~standingbear/home9.htm
Indian History
http://midnightstar.homestead.com/TrueOceanCityLocals.html

http://www.telusplanet.net/public/dgarneau/indian16.htm

Cheers,
G
The naming of the dog was mostly influenced by his parents and
lineage: His father was a pure-bred trophy-winning hunter named
"Big Zeke" and his mother was a pure-bred show-winning dog named
"Zelilah". So a name in the "Z"s seemed appropriate, and Zachary
(Zack for short) seemed like a good one.

As for Saint Justin, my mother and father were raised Catholic
(though no longer practicing) and I am generally non-religious
myself, but any names they chose had to be approved by my Catholic
grandmother...so a saintly name was a must. My mother wanted to be
able to name me after a non-religious figure who happened to have a
Catholic name. She loved the adopted name of a 60s fashion
photographer and manager, Justin de Villeneuve (real name Nigel
Davies), and recalled that there was a Roman emperor named
Justinian...so once she researched and discovered there was indeed
a saint with that name, she picked it for me and my grandmother
approved (born in 1968, I am the child of hippies!).
I'm impressed by your lineology - born in England yet destined to
live out the rest of your existance in Florida. It's as if your 1/8
Amerindian ancestor decided where you'd end up. Hey, man, where's
that wigwam ..
Yep...my mother is the American indian - she and my father decided
to move to the US in 1970 with me in tow, where we lived in New
Jersey, California, and finally Florida. I went to college in New
Orleans Louisiana, then moved back to California after college,
until 1994 when the big earthquake crushed my home and chased me
back to Florida where I still had some family. Been here since,
but no wigwam. My tribe was originally from the New Jersey area,
but were exiled to Oklahoma where they currently reside.

--
Justin
--
me :
http://www.pbase.com/image/27464432
Roscoff
http://www.pbase.com/geo_paris_fr/roscoff21072002
 
Thanks for the links and for the offer. The same stands on our side of the pond, if you ever find yourself in Florida.

I have friends in England and Germany and am planning to get over there to visit...I usually spend a little extra time touring around Europe a bit while I'm there. I've never known someone in France, so I've had nothing more than the occasional tourist drive through southern France around the beautiful Le Beau/Auvignon region and along the riviera.

Thanks for the new Jersey tribal links...I know Standing Bear's site very well - he's a pretty funny guy! I definately connect more to my Irish heritage, since I have so much of it, and I know most of those relatives (besides, I look more irish than anything else).

Surprisingly all the moving around was pretty cool...I liked seeing new places and meeting new people, and it has instilled a strong desire in me to travel and to learn about as many cultures and geographical locations as possible. I have tried to travel to at least 1 new country every year, and would like to reach every continent (I haven't been to Australia, Antartica or Asia yet).

I'll cut out the replies in this thread so it can stop popping up to the top and bothering everyone! Feel free to e-mail me any response or communication...it is always nice to have contacts or friends in other places to talk, debate, ask questions, etc.

--
Justin
 

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