Operator ColMax

This operator returns the maximum pixel value found inside each image column. The operator replaces each pixel value by the maximum value found in the very same column so far. Only if a current pixel is a new maximum, the output IsMaxO is set to 1. Otherwise, it is 0.

It is possible to clear the current maximum 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 maximum 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 ColMax operator.

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

Operator 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
IsMaxO, Binary output to indicate a new maximum

Supported Link Format

Link Parameter Input Link I Input Link ClrI Output Link O Output Link IsMaxO
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

Parameters

None

Examples of Use

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

  • 'Laser Triangulation'

    Examples - A high speed and robust laser line detection algorithm. The algorithm determines center of gravity coordinates to obtain sub-pixel resolution results.

  • 'ImageSplitAndMerge'

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