Veras

Transparency Suite: Example Filters made with Filter Factory
by Ky Hopwood 8/31/94 The Transparency Suite are a set of example filters made with Filter Factory that edit a layer's transparency data. This set of filters are not so much special effect filters but rather utility filters. The filters are as follows: Filter Name Add Remove Transparency Set Transparency Level Luminosity->OpacityOpacity->Luminosity Settings File Name EditTrans.afs SetTrans.afs LumOpac.afs OpacLum.afs

This document discusses what these filters are used for, and how they work ( they are simple ). Hopefully you will find these useful and will create other related plug-ins.

Why Transparency filters are needed .
Photoshop 3.0 introduced the concept of layers. Each layer is in essence a sheet of acetate thatcan be stacked and composited ( If there is any confusion in this matter, please refer to the Layers section in your manual ). All layers with the exception of the Background Layer, is a transparent layer with varying levels of transparency from 0 ( completely transparent ), to 255 ( completely opaque ). Each transparent layer has 2 different types of transparency: layer transparency and pixeltransparency. Layer transparency is how much that layer as a whole will affect other layers in the merged view of the document. For instance, you can fill a new layer with 100% opaque black, and set the Opacity of the layer via the Layers Palette to 10% and if the layer viewed over a white layer, the merged view of the document will be a light gray, even though the pixels are 100% black. Layertransparency affects all the pixels in the layer equally. Photoshop's Layers Palette gives you adequate control over this type of transparency, and these filters will not effect this type of transparency. Pixel transparency is the opacity of each pixel. This is a separate entity from the layers transparency. To get a feeling for what this does, imagine a single empty layer that has a white backgroundlayer beneath it. If you were to set the foreground to black and pull a Foreground to Transparent gradient, what you would get is a layer that looks grayscale. However viewing the Info Palette, you would find that the document is 100% black! The difference is it is also in various levels of opacity. There are few tools inside of Photoshop to edit this information. While there are many tools toreduce the opacity ( such as Fill in clear mode, soft selection delete, eraser tool etc. ), there are few tools to increase the opacity. Paint tools or fills will increase opacity, but they have other disadvantages such as brush strokes, and permanently altering the data. It is easiest to describe the lack of control by giving an example. Let's say I were to sketch a head with black as my foregroundcolor using a table with opacity set, as if I were doing a sketch with a pencil on paper. The result would look grayscale, but if I were to examine it with the Info Palette, I would discover that the file is completely black. This may make it hard to

edit the file for other uses, for example how can I increase/decrease the contrast if all the pixels are the same color. These filters are made todeal with these issues. They are not filters to amaze & woo your friends, but they can be quite helpful while working with Photoshop. Note: some things to keep in mind when working with these filters. - To use these filters, Preserve Transparency must be off. However Preserve transparency is often useful in editing these files at other times, so be aware of it's state. - Sometimes using thesefilters results in garbage from very transparent data suddenly rearing it's ugly head when it is made completely opaque. Consider editing the following filters to have a threshold setting.

The Filters Examples:
Set Transparency: This filter uniformly sets all pixels in a layer to a uniform opacity. This can be useful for creating mask for another layer. The formula is as follows: R: G: B: a: r g...