# dmap¶

Syntax: dmap(input image, output image, background value)

Calculates distance map or distance transform of a binary image. In order to calculate squared distance map, use dmap2 command. Uses algorithm from Maurer - A Linear Time Algorithm for Computing Exact Euclidean Distance Transforms of Binary Images in Arbitrary Dimensions.

This command can be used in the distributed processing mode. Use distribute command to change processing mode from local to distributed.

## Arguments¶

### input image [input]¶

Data type: uint8 image, uint16 image, uint32 image, uint64 image, int8 image, int16 image, int32 image, int64 image, float32 image

Input image where background is marked with background value given by the third argument.

### output image [output]¶

Data type: uint8 image, uint16 image, uint32 image, uint64 image, float32 image, int8 image, int16 image, int32 image, int64 image

Output image (distance map) where pixel value equals Euclidean distance to the nearest background pixel. Input and output can be the same image if in-place transformation is preferred and input data type is suitable. Integer pixel data types result in approximate distance map only. If floating point pixel type is used, the results might contain artifacts for very large images due to floating point inaccuracy. If that is encountered, consider calculating squared distance map using integer data type and then converting to floating point format, followed by square root operation. That is, dmap2(img, img); convert(img, float32); squareroot(img); Notice that this sequence may require more memory than the standard operation of this command because of the explicit conversion step.

### background value [input]¶

Data type: real

Default value: 0

Pixels belonging to the background are marked with this value in the input image.