Standard operators¶

You can use standard arithmetical operators for addition (+), subtraction (-),multiplication (*), and division (/).

The module also supports unary minus (-), modulo (%), and power (**) operators.

Note that all operations are done with 32-bit integers or 32-bit floatingpoint values, as necessary. For example, if you add two 8-bit images, theresult will be a 32-bit integer image. If you add a floating point constant toan 8-bit image, the result will be a 32-bit floating point image.

You can force conversion using theconvert(),float(), andint()functions described below.

Bitwise operators¶

The module also provides operations that operate on individual bits. Thisincludes and (&), or (|), and exclusive or (^). You can also invert (~) allpixel bits.

Note that the operands are converted to 32-bit signed integers before thebitwise operation is applied. This means that you’ll get negative values ifyou invert an ordinary grayscale image. You can use the and (&) operator tomask off unwanted bits.

Bitwise operators don’t work on floating point images.

Logical operators¶

Logical operators likeand,or, andnot workon entire images, rather than individual pixels.

An empty image (all pixels zero) is treated as false. All other images aretreated as true.

Note thatand andor return the last evaluated operand,while not always returns a boolean value.

Built-in functions¶

These functions are applied to each individual pixel.

abs(image)

Absolute value.

convert(image,mode)

Convert image to the given mode. The mode must be given as a stringconstant.

float(image)

Convert image to 32-bit floating point. This is equivalent toconvert(image, “F”).

int(image)

Convert image to 32-bit integer. This is equivalent to convert(image, “I”).

Note that 1-bit and 8-bit images are automatically converted to 32-bitintegers if necessary to get a correct result.

max(image1,image2)

Maximum value.

min(image1,image2)

Minimum value.