.. highlightlang:: us

.. index:: ImageGetPixelGray

.. _imagegetpixelgray:

ImageGetPixelGray
=================

.. us.tag  ImageGetPixelGray NOTREADYENGLISH Image ImageGet New520 Changed532

:ref:`ImageGetPixelGray` returns the gray value of a pixel.

.. function::  gray = ImageGetPixelGray(hImg, x, y)
               grayMat = ImageGetPixelGray(hImg)

.. us.return

**Return Value**

*gray* is the gray value of the specified pixel in the range 0 to 255. If x or y
is out of range the function returns the gray value of the pixel x=1, y=1. In
case of an error the functions returns -1.

.. us.params

**Parameters**

.. uparam:: hImg

   *hImg* identifies the picture created with :ref:`ImageCreate`.

.. uparam:: x

   *x* is the horizontal pixel position in the range 1 to :ref:`ImageGetWidth`.

.. uparam:: y

   *y* is the vertical pixel position in the range 1 to :ref:`ImageGetHeight`.

.. us.example

**Example**

The following saves the gray value in a text file. The data file can be loaded
with :ref:`filemore-file-functionsload-3d-data-matrix`. If the image size is big
the image size should be reduced to approx. 500 * 500.

::

   def image_save_pixel(hImg, ssFile)
   {
       fp = fopen(ssFile, "wt");
       if (!fp) {
           return FALSE;
       }
       dx = ImageGetWidth(hImg);
       dy = ImageGetHeight(hImg);
       for (j in 1:dy) {
           for (i in 1:dx) {
               g = ImageGetPixelGray(hImg, i, j)
               fprintf(fp, "%d\t", g);
           }
           fprintf(fp, "\n"); 
       }
       fclose(fp);
       return TRUE;
   }

.. us.history

**History**

.. list-table::
   :header-rows: 1

   * - Version
     - Description
   * - 5.3.2
     - 
   * - 5.2.0
     - New

.. seealso::
   :ref:`overview-pictures`,
   :ref:`ImageGetWidth`,
   :ref:`ImageGetHeight`,
   :ref:`ImageGetPixelColor`,
   :ref:`ImageSetPixelGray`

:sub:`id-552611`