smear brush.

[e1two]

Hi,

I'm really impressed with the tvpaint demo and really like the natural media feel of the drawing tools.
One thing bugs me though about the smear tools.

It mixes the colors well enough but if you pick green for example on an empty canvas and keep drawing
without lifting the pen, you can see the color fade from green (or any other color) to black.

The second image shows the large paintbrush with a smear value ranging from 0 (top) to 2 (bottom stroke)
every time using the same yellow. Is this how it should behave? Feels awkward to me at least.

smear3.jpg (32.04 KiB) Viewed 28142 times

Is it possible to change this behaviour so the brush keeps it's chroma value?

thanks for your help,

e1

[e1two]

Hi,

I played around a little more with this and I have noticed a couple things :

If I fll the layer with a base color, uncheck the paper setting and keep the opacity at 100,
the smear functionality is pretty reliable. However if I change the above settings the
brush very quickly fades from my selected color to black.

I think the underlying problem is how the smear works with opacity. I am not a technical
person but I get the impression that whenever the smear brush finds or works with opacity
it starts blending black into the smear.

It would be nice to have the option for the smear not to do this and keep to the selected
color.

It would be great if someone could look into this,

e1

[slowtiger]

Technicall, "smear" means "go from RGB values A to RGB values B". What do you expect it should use as B values when there's no colour at all = transparency?

This is a tool which only works in the presence of opaque colour.

[e1two]

Hi,

Thanks for the reply

I'm trying to get my head round this, not an easy feat in my case ...

So smear mixes between the color you've selected and whatever color is already on the canvas,
and if you have a transparent pixel on the canvas it will smear black into your A color

That still leaves me with a few open questions :

Can you tell the smear brush in that case to blend between A and A if it hits a transparent color?
And why does the brush still interpolate to black,even if fill my canvas with white and lower the
smear brush's opacity?

Is there another tv paint tool that allows you to blend in your picked color into your painting without
switching brushes?


e1

[slowtiger]

Hm, the programmer part of me tells me to not even attempt that ...

We have colour A (on the brush), colour B (on the canvas), alpha (on the canvas), and pressure (on the pen). These 4 variables have to go into 1 algorithm. Colour b is constantly changing during painting. The pseudocode would do something like that:

Pick B, pick pressure (between 0 and 1), calculate the pressure weighted median between A and B, apply the result and make it the new B.

To include transparency, it need to do something like this:

Pick B, pick transparency (between 0 and 1), pick pressure (between 0 and 1), calculate the transparency weighted median between A and B (=C), calculate the pressure weighted median between C and B, apply the result and make it the new B.

I'm not even sure how to say this in english, but I am sure that there's more stuff needed to avoid values outside RGB range, or totally silly values with no visible result. Maybe this graph adds logic:

verlauf.jpg (22.58 KiB) Viewed 28098 times

The colour inside the yellow border shows the result.

[e1two]

Hi Slowtiger,

I think i like "pseudocode", at least when you explain it, because I think I get it.
Would you not try to implement this because it would be a very slow brush or
because it is hard to code?

thanks again,

e1

[e1two]

Hi,

I'm not quite ready to let this fade away into the forum archives.

Does TvPaint handle transparency in a particular way that makes it hard to implement this?
If not, I can't help wonder how other applications like "mypaint" or "sai paint" manage to create
smear brushes that don't show this "side effect"

For me at least it's a bit of a deal-breaker, as the big selling-point for an independent animator
to buy tvpaint is to be able to do everything within one application.
From creating the storyboard, modelsheets, animation etc..

I would love to be able to create my backgrounds in tvpaint without having to worry about not
using opacity.

e1

[idragosani]

I was testing this the other day and I wasn't seeing the smear brush fade to black in the absence of other colors to smear into. The brush stayed the same color on an empty frame. I can test again tonight and post the results, but the smear only changed color if there was another color to blend with. I am using TVP 10.

[Paul Fierlinger]

I don't get it either; it works as expected but I don't work with colors all that much. Is this what you want to happen?

SMEAR TEST.jpg (32.62 KiB) Viewed 28050 times

[e1two]

Thanks for having a look at this.
I'm going to install the demo on my desktop to see if it's maybe a hardware issue

e1

[e1two]

Hi again

Just tried this on my desktop and I get the same result.

It's really easy to reproduce :

create a new image
set the background to check instead of color to make the effect more visible
pick any of the smear brushes from the toolbin
pick a color
draw a long continuous stroke (going up and down) from left to right without lifting the pen

on some brushes the effect takes a little longer

Maybe it's just me, but I can get really hung up about these things

e1

[Animark]

(Edit: deleted something wrong about A and B Color.)

I follow this thread since it started to get a deeper understanding of what the smearbrush exactly does.

I tested a little bit (TVP Pro 10.0.4) and can absolutely confirm the behavior described by e1two.
- When painting on transparent areas the color fades to black. The higher the smear-value - the faster it fades. This don't makes much sense for me.
- When painting on a color (white in my example) the A color fades to the existing color. I think, the smear function is made for this behavior.

Here is a picture showing the different fadings. I used the "Large Paint Brush" from the Tool Bin without any modifications.
.

SmearScreenshot.jpg (72.34 KiB) Viewed 28038 times

[Paul Fierlinger]

OK, I see what's going on; you are using those preset custom brushes someone like my wife, Sandra, a high-end background painter, never even touches. She either makes her own or uses those that other painter people around here have uploaded to share with all of us. A guy named Asaf makes especially spectacular water color brushes.

What you are using are brushes that are made with two colors. If you don't want to have two colors (which you obviously don't) just change the second color to the same color as the first (says Sandra) but If you don't want to fuss with that than it's easier to just use the smear brush in the tool panel -- which is what I did with my little smear job. If this is the only issue that's holding you back, just take the leap of faith, because TVP is clearly the one software does it all software -- though there are people here who specialize in taking the strange pleasure of switching between three or four different applications within two minutes of work.

I use only two other software; Sony Vegas Pro as my NLE, and Directory OPUS as my browser. You won't need an NLE if your films aren't longer than 3 minutes, but anything after that gets to be much easier with a simple NLE that costs around $60 to $80 (again Sony Vegas would be my choice if you work on a PC).

[meslin]

I have encountered this "dirty-brush" phenomenon before when I was making this video: http://www.youtube.com/watch?v=Ee8GLqORVoE and also this one: http://www.youtube.com/watch?v=_WekN_tDCn4. The colors seemed to snap to certain values that didn't make sense--not always black, sometimes cyan... I think I complained once, and was told that it is a natural effect of the blending algorithm, and I accepted that. But if it could be cheated around, I'd be most happy, since I do love the straight-ahead blended-paint style animation.

David

[idragosani]

OK, I've reproduced it also. It's inconsistent, some colors from the Color Bin don't exhibit this behavior at all (probably the "pure" colors), whereas others do, and picking colors from the Mixer always seems to reproduce. I think it would be more realistic to have it fade to full transparency rather than black, like a brush running out of paint.