a. Please what is the difference between RGB Mapping and luminance mapping.

b. Please can you explain the functions of MB 1D Frame Mod and MB Attribute Index parameters.

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All of these controls are explained in the Brush Source section of the Paint Synthesizer chapter in the User Guide. But i'll provide some detail below for you.

Colors that people perceive in the world can be represented in a 3-component color space. This is because the human visual system has 3 different kinds of color sensing cones. Here's an article on color vision if you aren't familair with it.

There are several different 3 component color spaces that can be used for digital image processing.

RGB refers to red, green, blue color space. It loosely corresponds to the 3 different types of color cones. It also loosely corresponds to the 3 phosphor primaries in color television displays. Here's an article on the RGB color model.

YIQ is another 3 component color space. It was also developed for color television systems. Y is a luminance channel, I and Q are 2 chrominance channels.

The 2 brush mapping you refer to analyze all of the different images in the brush (frames if movie brush, images in a folder is folder brush), compute the overall error between each image and the color that should be painted to represent the source image in that area, and then choose the image closest in overall color. If it's RGB mapping, then the error computation is in RGB color space. If it's luminance mapping, then the error computation is in luminance space (the chrominance is ignored).

Movie Brush indexing can be 1 dimensional, or 2 dimensional.

MB 1D Frame Mod is associated with 1-dimensional movie brush indexing.

The MB 1D Frame Mod parameter lets you choose a modulator to index through the individual frames in the movie brush, or the individual images in the image folder brush. The frame position or index is pretty obvious in a movie. For the images in an image folder brush, it's going to to be the alphabetical ordering of the individual image names. Giving them all the same name and adding numerical indexing at the end is one easy way to control that.

So if you choose pen pressure for the MB 1D Frame Mod, then as you press the pen down light and then harder into the canvas, you will move from the beginning frame to subsequently higher indexed frames until max pressure will index to the last frame in the movie brush.

If you choose luminance, them the luminance of the source image will be used to index into the stack of images. So black (0 luminance) will index to the first frame of the movie, while white (255 luminance) will index to the last frame of the movie.

Now, unless you specifically generated your movie brush so that the individual frames in the movie were ordered from the darkest to the lightest, just using luminance to index into movie frames might generate somewhat random results.

The MB Attribute Index lets you choose how the individual movie frames are ordered for the purposes of the frame modulation. Cycle Fwd (forward) just uses the physical index positions. Luminance or Orientation will remap the frame positions internally so that they are ordered by increasing luminance or orientation.

So, if you changed it to use Luminance, and you were using the pen pressure frame modulation, then you would always modulate from the darkest movie frame image to the lightest as you pressed down with increasing pressure. This is because the individual frame had been internally re-index based on their luminance.

The frame modulation options that have mapping in their names (RGB Mapping, Luminance Mapping), work differently than the other modulators like pen pressure for example. They work as i explained above, analyzing the entire set of images in the brush, and choosing the one that gives the lowest error in the appropriate color space.

2-dimensional movie brush indexing lets you have 2 different modulators to modulate through the movie frame indexing. Here's a hypothetical use of 2d modulation. you could organize your movie brush to allow pen modulation with pen pressure and pen tilt orientation. Your movie could be composed of a set images of different sized objects, where each object would be imaged at several different orientations. The pen pressure would be indexing through the set of different sized frames, and the pen orientation would be indexing through the individual object orientations.

You can also use 2d modulation so that frame time in an animation is used for 1 dimension of the indexing, and some other modulator is used for the second frame of indexing. You then stack several different movies together sequentially into a single longer movie file. they all have to be the same # of frames. So you can use the animation frame time to be indexing  the frame timing in the individual movies, while the other modulator is being used to index between the different movies. This lets you have a series of movies being played back in the movie brush of an animation. So you could do things like photo mosaic movies.

This has been discussed previously here on the user forum in great detail. Look through the archives for more discussion about it.


Thanks for the reply. 

Please how do you paint ensuring that the brush nibs follow the contour or orientation of the source image when using the mouse to paint.


Are you asking about modulating the orientation of the brush nib itself to match the source image? Or making sure the paint path follows the orientation of the source image.

The orientation modulation of the brush nib is controlled by the appropriate parameter settings in the Brush Modulation control panel.

The paint path direction is modulated by the setting sin the Path Angle control panel.

Please I want the brush nibs itself to match the orientation of the source image.

You use the orientation modulation control sin the Brush Modulation control panel.

Those Brush Modulation control panel settings are all you need to work with if you are doing normal painting.

If you are working with region fill as brush pen mode in path start regionizaiton presets, then you need to use a special Brush Option in the Region as Brush Mode control panel if you want the Brush Modulation orientation modulation to affect the rgb contents of the temporary brush nib generated by the region as brush pen mode.

Please what settings allow rotating  the brush nib interactively  to any angle as you paint.

Just choose the appropriate option in the Orient Modulation parameter in the Brush Modulation control panel. The same modulator options you see everywhere else in the paint synthesizer are in there. For example, Path Orient if you want the rotation to track the path movement, tilt orientation if you have a wacom pen and want the brush rotation to track the orientation of the wacom pen, etc.

Please which of the modulators would work best when using the mouse since I don't have a Wacom tablet and also don't know much about how the modulators work 


If you want to interactively modulate you kind of need something like a wacom pen and tablet. You can use pen pressure, tilt, tilt orientation, and barrel rotation (with art pen) to interactively modulate various parameters in studio artist.

Some of the other modulator options are associated with visual attribute characteristics of the source image (image orient, image hue, texture energy). There are some old ones (device2) that worked with a secondary input device on older wacom tablet models. Some will randomize (random). Some track the path itself (path orient or path length).

Bus1 lets you use another image in another layer to modulate. TG1 uses a temporal generator in the paint synth for modulation. The controls for both TG1 and Bus1 are in the Misc control panel.

The pen horizontal and vertical position on the canvas can be used to interactively modulate the brush orientation using the TG1 modulator with the appropriate TG1 Type settings. If you are manual drawing, this is limiting, but with some auto drawing presets it's useful.

We've talked about adding Midi or OSC modulation options to temporal generators, but that's not available at this time. maybe in the future.

The paint synthesizer includes a lot of ideas originally developed in music synthesis and music synthesizers. this includes parameter modulation.

Modulation is basically just using one signal to adjust the amplitude of another. Signals used for modulation could be something like the interactive characteristics of a wacom pen (pressure, tilt, tilt orientation), or visual characteristics of an image (luminance, orientation, hue, texture energy), or procedural oscillators (random noise generators like uniform, gaussian, rossler, simple shapes like ramp, triangle, sin).

Signals being modulated could be things like brush size, brush orientation, path length, path angle, color or position randomization, etc.

Here are some blog posts that discuss modulation in Studio Artist.

Here are some tip posts that discuss modulator.


Thanks for the response.

Please how do you setup studio Artist to avoid repeating the same brush frame but to alternate brush frames that best fits a specific colour space within the source image during manual painting of photo mosaics.

Again i've created a some brush images using in png format using Illustrator but when i use it in SA i see some white colored edges around my brush frame. Please how can i resolve this problem.



Without access to the specific paint preset you are using as well as the png brush images, it's hard to comment on the colored edges. Could be a function of how the particular paint preset is programmed.

As far as reducing repeating brush images. The whole point of the rgb mapping brush modulation is that it picks the best image that best represents the source image in a given area. if you have a large area in the source image that is best represented by a single image, then that image is going to be repeated.

You can randomize the color to try and break that up.

An alternative is to use something like random or cycle forward for your brush modulation, and then rely on brush load processing to modify the brush image coloring for the individual brush nibs so they better represent the source image.


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