Level TOP

From TouchDesigner 088 Wiki

LevelTOP 03.jpg

Summary

The Level TOP adjusts image contrast, brightness, gamma, black level, color range, quantization, opacity and more. See also the Luma Level TOP which preserves hue and saturation more accurately, but is slower.

The Level TOP's features have been built into one TOP to maximize performance in a single pass. It takes all its parameters to make a lookup table on the CPU, so animating parameters in the Level TOP will decrease its performance as the lookup table is recreated each frame that a parameter changes.

PythonIcon.png levelTOP_Class

Parameters - Pre Page

Invert invert - Inverts the colors in the image. Black becomes white, white becomes black. Colors invert across the color wheel, so red becomes cyan, blue becomes yellow, green becomes magenta, and so on.

Black Level blacklevel - Any pixel with a value less than or equal to this will be black.

Brightness 1 brightness1 - Increases or decreases the brightness of an image. Brightness can be considered the arithmetic mean of the RGB channels. The Brightness parameter adds or subtracts an offset into the R, G, and B channels. Low brightness will result in dark tones, while high brightness will wash the color out towards white.

Gamma 1 gamma1 - The Gamma parameter applies a gamma correction to the image. Gamma is the relationship between the brightness of a pixel as it appears on the screen, and the numerical value of that pixel. This is often represented by a gamma curve. The difference between brightness and gamma is that gamma also affects the ratio of red to green to blue. A straight, linear gamma curve with a value of 1 means no change.

Contrast contrast - Contrast applies a scale factor (gain) to the RGB channels. Increasing contrast will brighten the light areas and darken the dark areas of the image, making the difference between the light and dark areas of the image stronger.

Parameters - Range Page

In Low inlow - Any pixel below this value appears black.

In High inhigh - Any pixel above this value appears white.

Out Low outlow - Clamps pixel values to this value or higher.

Out High outhigh - Clamps pixel values to this value or lower.

Parameters - RGBA Page

Low R lowr - Clamps the minimum level of the red channel.

High R highr - Clamps the maximum level of the red channel.

Low G lowg - Clamps the minimum level of the green channel.

High G highg - Clamps the maximum level of the green channel.

Low B lowb - Clamps the minimum level of the blue channel.

High B highb - Clamps the maximum level of the blue channel.

Low A lowa - Clamps the minimum level of the alpha channel.

High A higha - Clamps the maximum level of the alpha channel.

Parameters - Step Page

Step Size stepsize - Posterizes the image into bands or stripes. Number of bands equal to the inverse of this parameter (i.e., 0.25 = 4 bands). Use a default Ramp TOP to easily see this parameter's effect.

Threshold threshold - Offsets the position of the step boundaries.

Clamp Low clamplow - Clamps the image's minimum value. (value as in hue, saturation, and value)

Clamp High clamphigh - Clamps the image's maximum value. (value as in hue, saturation, and value)

Soften soften - Softens or blends the boundaries between steps.

Parameters - Post Page

Gamma 2 gamma2 - A second gamma correction that is added after the Range, RGBA, and Step page adjustments have been applied.

Opacity opacity - Adjust the opacity, or transparency, of the image.

Brightness 2 brightness2 - A second brightness adjustment that is added after the Range, RGBA, and Step page adjustments have been applied.

Parameters - Common Page

Resolution - quickly change the resolution of the TOP's data.

  • Input - uses the input's resolution.
  • Eighth, Quarter, Half, 2X, 4X, 8X - multiply the input's resolution by that amount.
  • Fit Resolution - Resizes the input to the size specified in Resolution using the best possible match that does not crop any of the input. It will resize the image to be larger than the input resolution if a larger resolution is specified. It's a "fit inside", Aspect Ratio is maintained.
  • Limit Resolution - Limits the input to the size specified in Resolution using the best possible match that does not crop any of the input. It's a "fit inside", Aspect Ratio is maintained.
  • Custom Resolution - enables the Resolution parameter below, giving direct control over width and height.

Resolution - enabled only when the Resolution parameter is set to Custom Resolution. Some Generators like Constant and Ramp do not use inputs and only use this field to determine their size. The drop down menu on the right provides some commonly used resolutions.

Use Global Resolution Multiplier - Uses the Global Resolution Multiplier found in Edit>Preferences>TOPs. This multiplies all the TOPs resolutions by the set amount. This is handy when working on computers with different hardware specifications. If a project is designed on a desktop workstation with lots of graphics memory, a user on a laptop with only 64MB VRAM can set the Global Resolution Multiplier to a value of half or quarter so it runs at an acceptable speed. By checking this checkbox on, this TOP is affected by the global multiplier.

Output Aspect - sets the image aspect ratio allowing any textures to be viewed in any size. Watch for unexpected results when compositing TOPs with different aspect ratios. (You can define images with non-square pixels using xres, yres, aspectx, aspecty where xres/yres != aspectx/aspecty.)

  • Input - uses the input's aspect ratio.
  • Resolution - uses the aspect of the image's defined resolution (ie 512x256 would be 2:1), whereby each pixel is square.
  • Custom Aspect - lets you explicitly define a custom aspect ratio.

Input Smoothness - This controls pixel filtering on the input image of the TOP.

  • Nearest Pixel - uses nearest pixel or accurate image representation. Images will look jaggy when viewing at any zoom level other than Native Resolution.
  • Interpolate Pixels - uses linear filtering between pixels. This is how you get TOP images in viewers to look good at various zoom levels, especially useful when using any Fill Viewer setting other than Native Resolution.
  • Mipmap Pixels - uses mipmap filtering when scaling images. This can be used to reduce artifacts and sparkling in moving/scaling images that have lots of detail.

Fill Viewer - determine how the TOP image is displayed in the viewer.

  • Input - uses the same Fill Viewer settings as it's input.
  • Fill - stretches the image to fit the edges of the viewer.
  • Fit Horizontal - stretches image to fit viewer horizontally.
  • Fit Vertical - stretches image to fit viewer vertically.
  • Fit Best - stretches or squashes image so no part of image is cropped.
  • Fit Outside - stretches or squashes image so image fills viewer while constraining it's proportions. This often leads to part of image getting cropped by viewer.
  • Native Resolution - displays the native resolution of the image in the viewer.

NOTE: To get an understanding of how TOPs works with images, you will want to set this to Native Resolution as you lay down TOPs when starting out. This will let you see what is actually happening without any automatic viewer resizing.

Viewer Smoothness - This controls pixel filtering in the viewers.

  • Nearest Pixel - uses nearest pixel or accurate image representation. Images will look jaggy when viewing at any zoom level other than Native Resolution.
  • Interpolate Pixels - uses linear filtering between pixels. Use this to get TOP images in viewers to look good at various zoom levels, especially useful when using any Fill Viewer setting other than Native Resolution.
  • Mipmap Pixels - uses mipmap filtering when scaling images. This can be used to reduce artifacts and sparkling in moving/scaling images that have lots of detail. When the input is 32-bit float format, only nearest filtering will be used (regardless of what is selected).

Passes - duplicates the operation of the TOP the specified number of times.

Channel Mask - Allows you to choose which channels (R, G, B, or A) the TOP will operate on. All channels are selected by default.

Pixel Format - format used to store data for each channel in the image (ie. R, G, B, and A). Fixed format values are limited to the range [0-1]. Refer to Pixel Formats for more information.

  • Input - uses the input's pixel format.
  • 8-bit fixed (RGBA) - uses 8-bit integer values for each channel.
  • 16-bit float (RGBA) - uses 16-bits per color channel, 64-bits per pixel.
  • 32-bit float (RGBA) - uses 32-bits per color channel, 128-bits per pixels.


  • 10-bit RGB, 2-bit Alpha, fixed (RGBA) - uses 10-bits per color channel and 2-bits for alpha, 32-bits total per pixel.
  • 16-bit fixed (RGBA) - uses 16-bits per color channel, 64-bits total per pixel.
  • 11-bit float (RGB), Positive Values Only - A RGB floating point format that has 11 bits for the Red and Green channels, and 10-bits for the Blue Channel, 32-bits total per pixel (therefore the same memory usage as 8-bit RGBA). The Alpha channel in this format will always be 1. Values can go above one, but can't be negative. ie. the range is [0, infinite).
  • 8-bit fixed (R) - has 8-bits for the red channel, 8-bits total per pixel.
  • 16-bit fixed (R) - has 16-bits for the red channel, 16-bits total per pixel.
  • 16-bit float (R) - has 16-bits for the red channel, 16-bits per pixel.
  • 32-bit float (R) - has 32-bits for the red channel, 32-bits per pixel.
  • 8-bit fixed (RG) - has 8-bits for the red and green channels, 16-bits total per pixel.
  • 16-bit fixed (RG) - has 16-bits for the red and green channels, 32-bits total per pixel.
  • 16-bit float (RG) - has 16-bits for the red and green channels, 32-bits per pixel.
  • 32-bit float (RG) - has 32-bits for the red and green channels, 64-bits per pixel.
  • 8-bit fixed (A) - An Alpha only format that has 8-bits per channel, 8-bits per pixel.
  • 16-bit float (A) - An Alpha only format that has 16-bits per channel, 16-bits per pixel.
  • 32-bit float (A) - An Alpha only format that has 32-bits per channel, 32-bits per pixel.