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GIMPshop photoshop and markers oh my
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Tulsileaf
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PostPosted: Wed Oct 14, 2009 8:01 am    Post subject: Reply with quote

Aja wrote:
GIMP doesn't seem to like me, but I think I managed to wrangle a solution out of it. Try this!

[snip long complex solution]

Hope that makes things easier. :D

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Aja
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PostPosted: Wed Oct 14, 2009 3:27 pm    Post subject: Reply with quote

I know, I'm so amazingly helpful. It just leaves you speechless, right? I wonder why no one ever asks for advice a second time... Huh


Actually, it's simple when you're doing it. Just four steps: convert to grayscale, select the Gray channel, mask out the selection, and turn Levels all the way up.

But I found a shorter version, even:

Assuming your lineart starts out on the Background layer, just right-click that and choose "Add Alpha Channel." Convert to grayscale, select the Gray channel, skip the stuff with the mask and just hit Delete. Then you can go back to RGB and turn up levels.

That's the first thing I tried yesterday, but the sequence that works in Photoshop doesn't quite work in GIMP. (Without an Alpha channel, deleting just turns the selection white, instead of... y'know... deleting it.) XD

*shakes a fist at GIMP for being slightly different from Photoshop*

Rant Rant Rant
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brady kj
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PostPosted: Wed Oct 14, 2009 5:39 pm    Post subject: Reply with quote

Well, See's magic wand tool selected but didn't allow for deletion. Aja's converting to grayscale turned ALL THREE layers gray, and switching to color didn't turn them back. So, I fearfully Undoed to avoid re-doing two hours of coloring. Is the graying step really necessary?
Yesterday I set up a background layer with the original image, a layer above that that's a copy of the original, and put a blank layer in between that I colored, following along with a buddy's advice. I colored for two hours using the crappy compromise of having the whole top layer be 50% transparent, because the last time a buddy helped me with this, he partially fixed the transparency problem AFTER the coloring was nearly done. And then the GIMP spontaneously decided to close down, and when I reopened it I discovered I hadn't saved my picture for an hour. And I spent an hour re-coloring it to get caught up to where I was before. I do not want to add another two hours of re-coloring.

I'll attempt it without gray scale, and hope my computer doesn't explode.

And I remain suspicious of all claims that anything works in PhotoShop.
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brady kj
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PostPosted: Wed Oct 14, 2009 6:16 pm    Post subject: Reply with quote

IMPORTANT UPDATE: I did everything that Aja told me to do (except the grayscale step) , and the final result depends on whether I select "white full opacity" " black full transparency" or "layer's alpha channel". None of them do what I want.
Selecting the WHITE OPTION has made the picture precisely the same as it was before.
Selecting the BLACK OPTION: the coloring underneath the top layer show 100% through everything, be it black or white. So it's just like coloring on the same layer as the lineart, so the coloring destroys the lineart. I want my colors to show through ONLY the white space, so my coloring doesn't mess with my nice black lines, just like how using a green marker on a nice black pen line doesn't turn the line green, and doesn't turn the green marker into a pale ugly green.
Selecting the ALPHA OPTION makes something that looks like the black option, except when you look at the layer's tab the top layer looks blank. Keep in mind that the top layer was a copy of the bottom layer, which had my line drawing.
I strongly doubt the grayscale step will make it any better. Unless I did something wrong, this method adjusts transparency of the whole layer equally.

EDIT: Nevermind, I just remembered how to set the layer's "mode" to "multiply." It's right above the Opacity thingy on the layer window. I really should write that down. And, apparently, in this mode the color depends on the opacity of the lower layer. Wow! This is useful!
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Aja
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PostPosted: Wed Oct 14, 2009 7:49 pm    Post subject: Reply with quote

brady kj wrote:
I did everything that Aja told me to do (except the grayscale step)


Dude. That's why it didn't work. XD You need the "Gray" channel. Turning that into a selection is how you capture all the white pixels to delete.

Also, I forgot to specify that the two methods I posted work with the lineart layer only. Not so great for a work-in-progress with color and/or several other layers. Sorry.

HOWEVER! I have found a third and yet-simpler way to do it! (Curse you, Brady. You're making me learn GIMP...)

No grayscale required with this one, and it doesn't affect any of your other layers.

Quote:
Right-click your lineart layer -> Add Layer Mask

Choose these exact options and click Add

Right-click the layer again -> Apply Layer Mask

Color -> Levels -> Drag that top left arrow all the way to the right


And you're done!

Try it and tell me how it works. Cheese!



P.S. It's still better than setting the layer to Multiply, because it actually erases the white pixels instead of just hiding them. That leaves you with many more fun options for your lineart layer later.

P.P.S. I am inordinately amused by the context-dependent file name gimp-mask.jpg

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Tulsileaf
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PostPosted: Wed Oct 14, 2009 8:52 pm    Post subject: Reply with quote

Aja wrote:
Curse you, Brady. You're making me learn GIMP...

You say that like it's a bad thing. Napping or Waiting
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PostPosted: Fri Oct 16, 2009 6:22 pm    Post subject: Reply with quote

Aja wrote:

Dude. That's why it didn't work. XD You need the "Gray" channel. Turning that into a selection is how you capture all the white pixels to delete.

Dude. That doesn't make sense.
Aja wrote:

HOWEVER! I have found a third and yet-simpler way to do it! (Curse you, Brady. You're making me learn GIMP...)
It's part of my plan to know more than anyone else in the world. I simply trick smarter people into figuring things out and teaching them to me.

Quote:
Try it and tell me how it works. Cheese!

It worked. Thanks. Except that the arrow that works isn't the top one. It's the bottom one labeled Output Levels. I'm not sure the Input Levels one on the top does anything. So, what is a "layer mask", and what are these "levels"?
EDIT: I tried making a second colored layer under the first colored layer, so I can color somebody's skin without messing with his hair and clothes. I put a layer mask on the top colored layer, and now I can color the bottom colored layer without messing with the top colored one, but it does mess with my lineart. Apparently having two layers with masks above a layer only protects the layer directly above it. How do I make that not happen?
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Aja
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PostPosted: Sat Oct 17, 2009 12:03 pm    Post subject: Reply with quote

Yay! I'm glad it worked.

brady kj wrote:
Dude. That doesn't make sense.


To be honest, I'm not entirely sure how it works either. If I had to guess, I'd say the problem in RGB mode is that each pixel is defined by three values (Red, Green, Blue) -- so black is represented as "0, 0, 0" and white is "255, 255, 255" and there are all sorts of colors inbetween represented by values such as "17, 200, 151." (Oh hey, that's kinda pretty.) The program is defining pixels in terms of hue (color) instead of value (lightness), so it's harder for it to extract black lines. WHEREAS in Grayscale mode, each pixel just has one value between 0 (minimum value, white) and 100 (maximum value, black). There are no fancy combinations inbetween, just higher or lower values on the gray scale.

When you create a selection from the Grayscale channel, it's easy for the program to select each pixel more or less fully based on its value. So a "0" (white) pixel is selected fully, and when you hit Delete, it's cleared completely. A "50" (gray) pixel is half-selected so that when you hit Delete, it becomes 50% transparent.

What you want, of course, is not a bunch of semi-opaque gray pixels around your black lines, but instead a bunch of semi-opaque black pixels to give your lines smooth edges. When you adjust Levels, you're setting the minimum/maximum light and dark values on your layer. By pulling one arrow all the way from one side to the other, you're setting the minimum "dark" value to be the same as the maximum, so all pixels on the layer turn black. You could go the other direction and make them all white, if you were feeling fancy.

As for layer masks, they're just a way of hiding parts of your layer without actually erasing them (since, in theory, you might want them later). When you "apply" a mask, you're saying "go ahead and erase everything that's hidden."

brady kj wrote:
Apparently having two layers with masks above a layer only protects the layer directly above it. How do I make that not happen?


Is your lineart under your color layers? Try putting it on top.

brady kj wrote:
It's part of my plan to know more than anyone else in the world.


Diabolical! Monocle

I approve.
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brady kj
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PostPosted: Sun Oct 18, 2009 3:22 pm    Post subject: Reply with quote

I'm really not having a problem with gray pixels.
Aja wrote:

Is your lineart under your color layers? Try putting it on top.

My lineart is on top. It is two layers up from my color layer. However, I discovered that the problem remains there whether it's there or a single layer away from the skin layer. I just don't understand why my black lines keep turning into a dark flesh color and my black hair remains unaffected.

Now, somebody suggested that the Select By Color tool would work if you change a channel to "alpha"? How do I do that?
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Aja
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PostPosted: Sat Oct 24, 2009 2:04 am    Post subject: Reply with quote

Hmmm... Alas, I'm still not familiar enough with GIMP to make a good guess at what's going on there. Afraid I can't be much more help, without actually looking over your shoulder at your screen. XD

Or, if you felt like it, you could always send me the file to look at.
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