pclipvalues

Clips pixel values inside the specified range.

Synopsis

pclipvalues low high [-m mask] [im_in|-] [im_out|-]

Description

pclipvalues restricts the pixel values of the input image im_in to the range defined by the parameters [low..high]. Pixels with a value lower than low will be set to low; pixels with a value higher than high will be set to high.

More formally, im_out is built using the following algorithm for each pixel p:

if (im_in[p] > high) im_out[p]=high
else if (im_in[p] < low) im_out[p]=low
     else im_out[p]=im_in[p];

Parameters

low and high specifies the range of the output pixel values. They are related to the input type image (for example Img2duc [0..255],Img2dsl [-2147483648..+2147483648]).
Note: if min > max then min and max are set respectively with the minimum and maximum values of the input image type. (For example, 0 and 255 for Uchar images or +2147483648 for Img2dsl).

Inputs

im_in: an image.

Outputs

im_out: an image with the same properties as im_in.

Result

SUCCESS or FAILURE in case of invalid parameter values.

Examples

Contrast sharpening of the tangram.pan image using the unsharp masking technique. The sharpened image is built by adding a highpass filtering image of the initial image tangram.pan. The highpass image is built by subtracting from the tangram.pan image a blurred version of itself. At the end, only pixel values within the range [0..255] are kept in the final result. All the processing is done with float images.

   pim2sf tangram.pan i1.pan
   pgauss 0.8 i1.pan i2.pan
   psub i1.pan i2.pan i3.pan
   pmultcst 0.7 i3.pan i4.pan
   padd i1.pan i4.pan i5.pan
   pclipvalues 0 255 i5.pan mean.pan

C++ prototype

Errc PClipValues( const Img2duc &im_in, Img2duc &im_out, float low, float high );

Version française

Ecrêtage des valeurs de pixels

Author: Régis Clouard