Channels

PieroF_Channels_v0.5.fxscript.zip: (click the link to Download)

What does it do ?

Channels is a freeware filter for Final Cut Express and Final Cut Pro whose purpose is to display selected color channels of a clip in the RGB or YUV color spaces. You can display any combination of the alpha, red, green, and blue channels (RGB) or luma Cb, and Cr (YUV), and possibly invert them.

As an example, you can apply this filter to the clip leaf alpha black.tif sitting on top of the clip table.jpg in the timeline (see the figure on the right) to see the effect of the alpha channel.

Before applying the filter the frame looks like this:


 

When you apply the Channels filter to the top clip leaf alpha black.tif you can get the following results:

or 

...where in the 1st figure the alpha channel alone is displayed for the leaf clip and the black Color is used to paint it (not its default), while in the 2nd figure also the red channel is shown. You can also invert the selected channel as in the following examples:

or

...where in the 3rd figure both the alpha and the blue channel are inverted, and in the last figure all the channels are selected and inverted.

Compatibility, Disclaimer

This Channels filter has been tested in Final Cut Express 4 and Final Cut Pro 6, but it will likely work also in other versions of FCE and FCP as long as they provide support for the fxscript scripting language (see also the Disclaimer).

Version History

v0.5 - Added 4 new alpha channel handling options to Display Channels.

v0.4 - Added the possibility to color the alpha channel.

v0.3 - Added YUV and Greyscale.

v0.2 - Added Invert All.

v0.1 - moved to the pf-toolbox.

v0.0 - first release.

Filter Usage

After its Installation drag the filter Channels v0.5 from the Video Filter > pf-toolbox folder of Effects into the Viewer on the clip you want to apply it to, and choose:


  1. •Display Channels (default: RGB): selects the color space used for the channel selection. This may be:

  2. ‣RGB: it allows to select the Alpha and RGB channels to display: the next RGB and YUV checkmarks refer to an RGB color space (Red, Green, Blue).

  3. ‣YUV: it allows to select the Alpha and YUV channels to display: the next RGB and YUV checkmarks refer to a YUV color space (Y = Luma, U = Cb, V = Cr)

  4. ‣Greyspace: it displays a greyscale image using only the Alpha and the Luma channels in the YUV color space. Green/Cb and Blue/Cr are ignored.

  5. ‣Extract Alpha: it displays only the Alpha channel as a transparent greyscale image; the color channels are set to Black (RGB = (0,0,0)). The Alpha, RGB and YUV checkmarks are ignored.

  6. The resulting clip may be used for Travel Matte - Alpha compositing.

  7. ‣Color Alpha: it displays only the Alpha channel as a transparent colored image; the color channels are set to Color. The Alpha, RGB and YUV checkmarks are ignored.

  8. ‣Make Matte - Luma: it displays an opaque greyscale image created using the input Alpha channel: input opaque areas are made white and input transparent areas are made black; the resulting image is always opaque (its Alpha = 255). The Alpha, RGB and YUV checkmarks are ignored.

  9. The resulting clip may be used for Travel Matte - Luma compositing.

  10. ‣Make Matte - Alpha: it displays a transparent colored image created interpreting the input as a greyscale image: input white areas are made opaque and input black areas are made transparent; the color channels are set to Color. The Alpha, RGB and YUV checkmarks are ignored.

  11. When Invert (see below) is checked, the result is the same as the Make Transparent filter, with its Invert control checked.

  12. •Invert (default: OFF): when ON all 4 channels are inverted before applying the Display Channels options. It work with all of them.

  13. Notes: inverting an Alpha channel means changing opacity into transparency and viceversa; if the clip has no alpha channel, inverting it makes the full clip transparent (i.e. invisible...)

  14. •Alpha (default: ON): selects the alpha channel for the clip.

  15. If no other option is selected the effect is the same as Display Channels = Extract Alpha: a greyscale image is displayed representing the alpha channel, where opaque areas are black, transparent areas show the underlying clip (or the canvas background color selectable with View > Background menu), and half transparent areas show the underlying clip through a grey cover.

  16. The Alpha control is ignored if Display Channel selects one of the Alpha channel handling options (Extract Alpha, Color Alpha, Make Matte - Luma, Make Matte - Alpha).

  17. Note: with the FCE default Background transparent areas are not distinguishable from opaque areas, because the default Background is also black: to see them you can use Display Channels = Color Alpha, which by default colors opacity with violet (in place of black).

  18. If Invert is checked (see above) opaque and transparent areas are inverted.

RGB and YUV:

  1. •Red/Luma (default: ON): selects the red channel for the clip (if Display Channels is RGB) or the Luma channel (if Display Channels is YUV or Greyscale).

  2. If no other option is selected and Display Channels is RGB, a red image is displayed for the opaque portion of the clip representing the red channel, while black covers the transparent portion.

  3. If no other option is selected and Display Channels is YUV, a greyscale image is displayed for the opaque portion of the clip representing the luma channel, while black covers the transparent portion.

  4. If Alpha is also selected the transparent portion is shown transparent as it is supposed to be.

  5. •Green/Cb (default: ON): selects the green channel for the clip (if Display Channels is RGB) or the Cb channel (if Display Channels is YUV). Its value is ignored it Display Channels is Greyscale.

  6. If no other option is selected and Display Channels is RGB, a green image is displayed for the opaque portion of the clip representing the green channel, while black covers the transparent portion.

  7. If Alpha is also selected the transparent portion is shown transparent as it is supposed to be.

  8. •Blue/Cr (default: ON): selects the blue channel for the clip (if Display Channels is RGB) or the Cr channel (if Display Channels is YUV). Its value is ignored it Display Channels is Greyscale.

  9. If no other option is selected and Display Channels is RGB, a blue image is displayed for the opaque portion of the clip representing the blue channel, while black covers the transparent portion.

  10. If Alpha is also selected the transparent portion is shown transparent as it is supposed to be.

  11. Note: any combination of the 3 controls above may be selected together with the Alpha control. The default settings (all 4 controls ON) show the standard image as it appears without the Channels filter.

Color Alpha and Matte Alpha:

  1. •Color (default: violet = (128,0,128)): it paints the opaque areas of the displayed image if the Display Channels is Color Alpha or Make Matte - Alpha. It is ignored on all other cases.

Other Channels Tools in FCE/FCP

This filter offers a simple solution to display single or selected channels, that I could not find in FCE; FCP has a similar function built into the Canvas window menu, where you can choose the RGB channels separate from the alpha channel. This however is not available in FCE.

On the other hand there are many filters both in FCE and FCP available to handle channels, most of them in the Video Filters > Channel bin of the Effects: you can modify, swap, mix, invert, copy channels and more. Just I couldn’t find a simple filter to display single channels.