PC/Win Filter: High Pass Lum

[Stroker]

I lost the thread, but somebody was complaining about High Pass over-saturating. This is also something that I hate working around and I just happen to have a very fast Gaussian blur algorithm. Finally got a little bit motivated to start my own filter called High Pass Lum.

Extreme beta, so please don't mind the mess of it. Functional, though. Run the filter, set q, and let it do it's magic. Once back to the Layer palette, set blending mode of layer to Luminosity.

I'm going to start cleaning it up and adding things in the next day or so. One thing seriously on my list is a few speed optimizations. I should be able to improve the speed to around 65% of it's current. Will also put RGB back together instead of just outputting Lum. Few other ideas but will have to wait to see how things go.

Since this is extreme beta and I haven't starting waxing it yet, I'm open to whatever.

PC/Win
RGB 8-bit
Filter > Tech Slop > High Pass Lum

[Stroker]

Above attachment updated.

- Made it HsY friendly so you don't have to mess with Luminosity mode if you don't want to.

- Added two tweaks to fade high and low. High being >128 and Low being <128 in the High Pass pass. These tweaks are relative.

[Kraellin]

stroker,

just downloaded and tried your new update. interesting plugin. i dont think i have a 'high pass' filter in psp, at least not that i'm aware of, so i dont really have anything to compare yours to. so, i'm curious; what does the one in ps do, how is it commonly used and how does yours compare?

i did run in it on the barros picture in the photo art forum and i liked what i got... just not much understanding of how it got there on a low q (whatever that is) it seemed to only affect the picture up to about a setting of 100 or so. the high seemed to sharpen the high tones while the low did the same on the lower end. is this primarily a sharpening filter, a contrast filter, or what?

i do like the effects, whatever it is. i'm attaching the barros picture that i used your filter on q = 1, high = all the way right, low = all the way right. then set the blending mode of that layer to burn and merged.

Craig

[Stroker]

High Pass is basically Gaussian Blur with an extra step to make it identity 128. The major identifying mark of High Pass is lots of 50% grey (see attachment). High Pass is commonly used for sharpening or enhancing local contrast.

When used for some things, High Pass will over-saturate pixels. This is because it's an RGB operation. What I've done is taken out the over-saturation aspect by operating solely on Luminosity. This can be done manually, but I use this technique quite a bit and it was getting tedious.

Theoretically it is very close to the manual method. However, my filter can't do sub-pixel operations. I've done a few comparitive tests and they came out well, but not totally thorough tests just yet.

This basically enhances contrast based on frequency. If you have a photo with lots of small detail, the try lower q. If it's a photo with large patches, try higher q.

* q is analogous to radius

Now, if the kids would leave me alone for more than a few minutes, I could get my next thing done to extreme beta.

[pjstaley]

Would I be safe in assuming that this is a Photoshop filter and it's compatible with CS?

[Stroker]

Would I be safe in assuming that this is a Photoshop filter and it's compatible with CS?

Yes. Should also be compatible with other programs that can use 8bf filter files. But I'm not very familiar with the FilterMeister compatability list as it changes with versions of FM and host programs.

Time to kick me in the pants for steam-rolling. Please be gentle.

I took a break, got refreshed, and then went on with a similiar filter that I call Lum Frequencies. This breaks the Lum down into 3 frequencies based on q. You can then tweak the upper and lower halfs of the different frequencies similiar to High Pass Lum.

Sometimes it's good and sometimes it's bad. Like any tool, knowing when it when it is good is half of the solution.

edit:
Logic bomb found in Lum Frequencies. It's in the low frequencies. Not sure how long it will take me to explicitly identify and blast.

edit2:
That didn't take long. Amazing what a difference a simple +25 can do in the right places. Attachment updated.

[Kraellin]

pjstaley,

it works for me in psp 9.

stroker,

tried the new one. oops, just saw you updated yet again. lol. ya gotta love beta. i'll have to give the new one a swing now.

from what i could see of the 2nd version, you added a mid tone filter. nice touch.

Craig

[Stroker]

As it turns out, the logic bomb wasn't completely taken care of. The +25 was only part of the problem. The other part of the problem was in only processing the low frequencies just once. This time I'm going to give it a more thorough work-out before updating. Maybe work on the UI a little bit and a few other little things.

Not really mid-tones, but mid-frequencies. Working in frequencies can be a bit hard to grasp at first. But if you can grasp it, it can be a good tool to have in your toolbox.

Attached is a chunk of a photo that I broke apart into frequencies.
Upper-Left: low frequencies
Upper-Right: mid frequencies
Lower-Left: high frequencies
Lower-Right: all 3 put back together

In that example, you should be able to see that the mezzo resides mostly in the high frequencies and partially in the medium frequencies.

So much work to do, so little time.

[Kraellin]

a couple questions here, stroker. what does

my filter can't do sub-pixel operations.

mean?

and when you're talking frequencies, are you talking about light frequencies as in the 400 to 700 nano meter range or something else?

and what is 'mezzo'?

Craig

[Stroker]

Sub-pixel operations can use decimal points. If you use Gauss radius = 2.5, then you are blurring out to 2 full pixels plus 1/2 of a pixel. Currently, I can't play that kind of jazz. I'm not even sure if my tools allow for it. Something I'll have to look into one of these days.

Not frequencies as in light. Rather, rolling hills (low) and jagged rocks (high) added together to make a complete terrain.

In the example that I attached in my last post, there are those horizontal white lines. I don't know for sure if that phenomenon has a name, so I just call it mezzo after a filter called Mezzotint.

Started the node to make this official:
Lum Frequencies

[Kraellin]

a half pixel? didnt know that was possible. i can understand doubling the image size and getting more intermediate pixels, but didnt know you could paint half a pixel.

ok, still lost on the frequencies definition. are you talking luminosity values only here?

mezzo. ok.

you definitely have a different way of looking at things, stroker (i think that's a good thing)

Craig

[Stroker]

Yup, sub-pixel can be done. If you have a filter that does custom convolution kernels, you can use it to shift/offset by a fraction of a pixel.

The frequencies that I'm operating on in Lum Frequencies is indeed Luminosity. Hence, the name. Normally frequencies are thought of as 1d, as in a sound wave on a silly-scope. But, like many things 1d, can be made 2d and higher.

Here is a link that talks about frequency:
http://freespace.virgin.net/hugo.eli...s/m_perlin.htm

I also highly recommend looking for Peter Hajba's article and reading it several times.

I do have a strange head. It's something I'm known for in certain circles. Too bad my idiocy over-shadows my genius a little too often. Mixed blessing.

edit:
More junk done. See the node.

Almost time to crawl back under my rock.

[Kraellin]

stroker,

well, we've been here before with your plugins. i start asking questions and you point me to something where i fall asleep so, i'm leaving it here. i did have a look around at perlin's site. that guy is a genius.

as for 1d vs. 2d. i remember an old science class where the teacher was showing us something on a chalk board and asking about how many dimensions it had. he was looking for 2 and i pointed out it had 3. that even though the chalk seemed pretty flat, it still had some depth. this was about 7th or 8th grade. he was duly impressed that i saw that. but, that's about as far as i go. an oscilliscope is generally considered a 2d representation. adding a third dimension, depth, would be almost meaningless, unless you assigned it a value of something and made it sort of an arbitrary value at that. so, i dont see how taking the lum values and adding another dimension helps at all. i dont mean that as a criticism, oh poo poo, but rather that i just dont understand.

but, i am using the plugin! and i do like it. i just tweak it till i get something i like. i dont really understand all that i'm tweaking, but i like the results so, thanks!

Too bad my idiocy over-shadows my genius a little too often.

so, an idiot-savante?

Craig

[Stroker]

Yup yup.

More junk done. Final form for now. See node if ya got the yarbles for it.

Time to disappear for awhile.