Preserved Topic: Level, Level, Level!!!

Hey guys. I found this site today. Awesome, A?

Well, hope somebody let me knwo how to solve this problem.

Today I tried to understand "level" effect, which is Image > adjust > level. I believe "level" effect makes square into round shape, right? I draw a square. Make a new channel for it. Blur it. Then I do "level" for it setting number box like 109,1.00,121. It seems beautiful round square. But when I see it carefully, it get funny grey line around it. I don't know why?!

Please need your help!!! From New Zealand.

Cheers.

Hiroki Kozai

Well I will attempt to explain, levels as simply as possiable. Photoshop manual goes over levels, as do several books.


Basicly level is similar to curves, with slightly less control. Both used to adjust the value of the colors in an image. Levels are given 3 contol points. The Highlights, Midtones (sometime called gamma), and Shadows. The White, Gray, Black arrows under the graph which is called a histogram. A histogram is a graph showing the number of colors, relative to their postion on the tonal scale from light to dark. Take a gradient from white to black, would give you perfect bell curve.

One use of Levels is color correcting images. Take an image that was too dark, levels could be used. Moving the mid point or gray arrrow, towards the shadows would make the image darker, toward the highlight it become lighter. The shadows and highlight are best left untouched unless you have to, as once you move them you begin to loose tonal values and compress the dynamic range of the image. But often his is a necessary evil. Color move are also possiable by choosing individule channels.

The reduction in tonal range is bascly what you were doing in the process you discribed. It is sort of a hack taking advantage of the way, blur filters are calulated, allowing you to trans form a hard edged square element into a hard edged round one.

Here's how it works:

Say you take a black square on a white background. If we use levels, one would see only two lines on the histogram, Highlight and Shadow as there is currently no gray values between them. Moving the the levels at this point only increase or decrease black or white.

However if a gaussian or other blue on run on the image. It would produce gray levels. Notice how the Blur filter, caused the corners become rounded.

That's where levels or curves comes in. Opeing levels now the histogram shows many levels in between highlight and shadow. Adjusting the Highlight and Shadow point now decrease the tonal range image, there for reducing the fuzzy edge caused by the Blur filter. Because the Blur eliminated the hard edge corners, you are left with a rounded edge. If done correctly you can create a curved cornered box at ruffly the same size as the original square version.

Note: I use gray as an example only, the level works in all channel of the mode you are using, be it CYMK or RGB. It also works with selections, masks or alpha channels what ever you choose to call them.

It is a usefull tool, in most cases it is far better to use paths to create complex curved paths, but it some times necessay. such as creating buttons or masks for when recording actions.

jstuartj

PS. Oh, Welcome to the Asylem.



[This message has been edited by jstuartj (edited 12-11-2002).]

Ummm...yeah, what he said...pretty in-depth explanation...and a good one.

And welcome to the Asylum, Hiroki. Enjoy.

Just to keep everyhting joined up this has also been asked here (although my pointing back here is the only reply):
http://development.gurusnetwork.com/discussion/thread/1755/

___________________
Emps

FAQs: Emperor

Well that's is sort of a different problem but releated. My guess is some problem created by anti-aliasing and/or cut and paste. Perhaps a selection is active when the levels move was performed. But it's hard to tell without watching the process.

If all you desire is to create a selection, with rounded corner, you might have better luck using quick mask, simply create you selection as normal, go to quick mask, then perform your levels or curve move. Then deselect quick mask and ta da rounded corners. Simply save selection if you need a channel.

Any tool you can use on a channel you can use in quick mask.

jstuartj



[This message has been edited by jstuartj (edited 12-11-2002).]

Hi, guys. Thanks for your reply. I appreciate that.

Well, Dear jstuartj. I am trying to understand your advice. Please would you give me a wee bit more hand?

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The shadows and highlight are best left untouched unless you have to, as once you move them you begin to loose tonal values and compress the dynamic range of the image.
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I am afraind I have no idea what it means such as total values and compress the dynamic range. Pleae could you explain more.

Thanks from New Zelannd.

Sincerely,

Native kiwi


Hiroki Kozai

Ok, not meaning to butt in here...but it's somewhat like this...your levels are shown on a gauge...with values from right to left...I'm not sure which, but I think that the lightest are to the left, and the darkest to the right (or the otherway around...). So, as you move the little arrows on the gauge (under the line...), you lose this information. Or rather, you replace it with new values. I think that is what he was suggesting...that one needs to be careful when using levels, that one doesn't lose too much...of either darkness, or lightness...little tweaks work wonders...but major ones normally totally destroy the intended effect...

In the simplest terms (and someone please stop me if I'm wrong):

tonal values == areas of light and darkness. "Tone," here, means lightness or darkness. ("Tonal" is the adjective of "tone.")

dynamic range == the absolute minimum and maximum of darkness in an image. If the dynamic range gets smaller, the light parts get darker and dark parts get lighter.

By dragging the arrows on the bottom bar of the Levels box, you reduce your dynamic range.

By dragging the arrows on the histogram, you can remove parts of your dynamic range -- you can remove the middle values between white and black. This sometimes makes your image sharper. You can also choose whether the image tends more toward light or dark.

Hmm... by typing it all out so simply, I've reached a new understanding of the Levels function myself! Yattaze!

In a sentance:

Level adjustments act very similar to the brightness/contrast function only with levels you have a lot more control oever what ranges and colour channels to add contrast too.


I myeslf use it a lot to clean off dirt marks and eraser scars from scanned pencil sketches. Personally, I don't worry too much about loosing image data by going too far because sometimes the details are just trival compared to a more striking overall image. It all really depends on what your after.

And, just like with most of the stuff in PS:

quote:

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Just fiddle with it, until it feels right. No, not that, Photoshop. -F1 Error

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Hey mahjqa, I wanna learn that stuff you do!!!!!!! I will give up anything for it...just tell please I like the buterfly sig....and I wanna know hot to do the animated flame....and the cross is amazing!!!! did you fallow a turtorial or you bought a book....TELL ME TELL ME....I BEG YOU!!!!

Ohh and I almost forgot....the laser beam too!!!

you are great! master mahjqa

[This message has been edited by Ruski (edited 12-12-2002).]

Wow, lay off the sugar, will you?
AND GET ME OFF THIS F$#@ PEDESTAL!

*cough*

Anyway... In the FAQ there's a couple of pages dedicated to the fire... here.

What's there to say about the rest? Don't expect to learn it in a day or two. Most of it is just trying for yourself, and learning while doing so. Take a stab at the sig contests or the weekly image, fix yourself a sig. That's why all those things are here. To make images, and to get comments and critiques to learn and to get better. Sure, some tutorials will help a lot (Weadah's tutorial for example) but you'll learn the most if you do it yourself.

Sure, if you've got any concrete questions I'll be glad to answer them, but simply "how do I make something that looks exactly like X" isn't really useful.

DL-44's (I believe it was him) said that if you wanted advice on how to make something, try to do it yourself first. Then, post it in the forum, and ask if anyone has any suggestions on improving it.

You got yourself a fan club, Mahjqa

Ruski, the flame animation can be found in the FAQ. The others I am not too sure of as I haven't see the butterfly you are referring to unless that was my burning moth sig.

When doing high detail work start with a resolution higher than 72, I typically use 144 or 216, and a large canvas. Draw what you want. Then resize the image to less than 75 pix in height. All of your detail will be preserved.

And yes, what moth said. Working in a higher resolution than what it's supposed to be has it's advantages. Mistakes are less obvious, and it's in general easy to work with.

(I don't mess with resolitions though, I just double the size of the canvas, and shrink it back when I'm done. Also, to avoid blurriness, when you make it bigger do it with complete numbers luke 2, 4 or 8 times, and shrink them back to 50%, 25% and 12,5% respectively.)

(oddly enough, the 'big' version of this gun is 11Kb, compared to the 'small' animated gif, which is 45Kb.)

Dynamic range is the total amount of seperate color values in an image.

What I mean buy you loose values my moving the highligh and shadow arrow is:

Say you have steped grayscale image, with 5 steps.

(0% 20% 40% 60% 80% 100%)

In levels you would see 5 bars on the histogram. If you move the shadow arrow to the left, to the next bar 80% and hit ok, it makes all pixels from 80% --> 100% = 80%. no longer be any values from 81%-100%, sure you adjust it again so that 80% now equals 100% but any detail between the old 81-100% has been lost. The only way to get it back is to go back to the original, undo or history.

jstuartj

First of all, forget everything to do with resolution. Leave it at 72dpi and don't think about it again unless you want to print your image.

That being said, try to think mainly in terms of image width and height. If you want your final image to be 200x200px then work with it a 600x600 or 1800x1800 if you want lots of detail.

Remember, as far a digital output (i.e. your screen) is concerned, resolution is a myth. Think height and width.

Whoa I didnt know that faqs here are so deep...hey moth click on mahjqa's sig to see all the sigs he has done, there is a side way butterfly that swings the wings on mahjqa fonts....that what i ment....and what does mahjqa stands for is it in arabian or something?

Hiho~ guys!!! Thanks for your help. I will try and try it again.
Have a good day.
Cheers.



Hiroki Kozai

Hey mahjka, I read your profile, you like fina fantasy kool, how about making a gunblade, I wanna see it !

Look at Moth's sig, he's got one right there. Admittedly, it's more of a gun-vegetable-peeler, but it's the real thing.

[thread hijack in progress]

Ruski; I tried to make one ages ago, but I got fed up with it before it went anywhere... I lost the PSD, and I don't think I'll ever finish it.
http://www.mahjqa.com/stuff/gunblade2.jpg

thats pretty good


Cell 910