return to first page linux journal archive
keywordscontents

Process Elements

Arithmetic: Add two images or an image and a constant.

BandCombine: Combine three SingleBand images to create a TripleBand image.

BandExtract: Generate a SingleBand image from a color image. Typical use is to generate a gray-scale version of a color image.

BandSelect: Pass one band of a TripleBand image and discard the other two bands.

Blend: blend two images using an optional alpha plane.

Compare: Compare two images based on conditional tests, generating a bitmap result.

Constrain: Map image data into a specific integer range by either clipping or scaling.

ConvertFromIndex: Convert pixel values indexing a color map into their corresponding intensity values.

ConvertFromRGB: Convert an image from RGB color space to some other color space.

ConvertToIndex: Convert intensity values into color-map indexes which store the mapped intensity values.

ConvertToRGB: Convert an image in a non-RGB color space to RGB. (We used this in our sample program.)

Convolve: Perform an image convolution using a user-supplied kernel. Can be used to implement effects such as blurring, embossing and sharpening.

Dither: Dither an image to some number of levels less than the input image.

Export Elements: Send data out of a photoflo to either a client or server resource. The most commonly used export element, ExportDrawable, sends color-map index data to an X window for display.

Geometry: Scale, rotate, crop, translate or perform a combination of these options.

Logical: Perform a logical operation on two images or an image and a constant. Logical operations include OR, AND, NOT, etc. The logical operations are the same as X's GC functions. For more information, refer to XSetFunction.

MatchHistogram: Perform histogram equalization on an image. The characteristic shape of the result can be specified by a technique.

Math: Perform a math operation (e.g., square, log) on an image.

PasteUp: Arrange (e.g., tile) n source images to generate the resulting image.

Point: The most versatile process element. Can perform an arbitrary mapping of image pixels using a LUT supplied by the client.

Unconstrain: Remove the levels attribute of an image.