Operator ColMin

This operator returns the minimum pixel value found for each image column. The operator replaces each pixel value by the minimum value found in the very same column so far. If a current pixel is a new minimum, the output link IsMinO is set to 1, otherwise it is 0.

It is possible to clear the current minimum manually by setting the ClrI link to 1. When a manual clear is not required, a constant 0 must be applied to ClrI.

With every new input frame, the detection of the minimum value restarts for each column.

Often, this operator is used in conjunction with the RemoveLine operator to remove all but the last line of a frame. This last line of a frame contains the results of the ColMin operator.

The following example shows the relation of input values to output values:

Image Restrictions:

  • Image Size

    All lines of an input image must have the same length. Images with varying line lengths are not allowed.

  • Empty Images

    Empty Images, i.e., images with no pixels, are allowed. The operator will output an empty image.

  • Image Protocols

    Only VALT_IMAGE2D and VALT_LINE1D image protocols are supported.

I/O Properties

Property Value
Operator Type O
Input Links I, Image Input
ClrI, Clear Input
Output Links O, Data Output
IsMinO, Binary output to indicate a new minimum

Supported Link Format

Link Parameter Input Link I Input Link ClrI Output Link O Output Link IsMinO
Bit Width [1, 64] unsigned, [2, 64] signed 1 as I 1
Arithmetic {unsigned, signed} unsigned as I unsigned
Parallelism any as I as I as I
Kernel Columns 1 as I as I as I
Kernel Rows 1 as I as I as I
Img Protocol {VALT_IMAGE2D,VALT_LINE1D} as I as I as I
Color Format VAF_GRAY as I as I as I
Color Flavor FL_NONE as I as I as I
Max. Img Width any as I as I as I
Max. Img Height any as I as I as I



Examples of Use

The use of operator ColMin is shown in the following examples:

  • 'ImageSplitAndMerge'

    Examples - Shows how to split an merge image streams. Appends a trailer to the image.