1991-2006
Silicon Graphics, Inc.
gluScaleImage
3G

# gluScaleImage

scale an image to an arbitrary size

## C Specification

                    GLint gluScaleImage
                    GLenum format
                    GLsizei wIn
                    GLsizei hIn
                    GLenum typeIn
                    const void * dataIn
                    GLsizei wOut
                    GLsizei hOut
                    GLenum typeOut
                    GLvoid* dataOut

## Parameters

`format`

  Specifies the format of the pixel data. The following symbolic values are valid: `GLU_COLOR_INDEX`, `GLU_STENCIL_INDEX`, `GLU_DEPTH_COMPONENT`, `GLU_RED`, `GLU_GREEN`, `GLU_BLUE`, `GLU_ALPHA`, `GLU_RGB`, `GLU_RGBA`, `GLU_BGR`, `GLU_BGRA`, `GLU_LUMINANCE`, and `GLU_LUMINANCE_ALPHA`.

`wIn`
`hIn`

  Specify in pixels the width and height, respectively, of the source image.

`typeIn`

  Specifies the data type for `dataIn`. Must be one of `GLU_UNSIGNED_BYTE`, `GLU_BYTE`, `GLU_BITMAP`, `GLU_UNSIGNED_SHORT`, `GLU_SHORT`, `GLU_UNSIGNED_INT`, `GLU_INT`, `GLU_FLOAT`, `GLU_UNSIGNED_BYTE_3_3_2`, `GLU_UNSIGNED_BYTE_2_3_3_REV`, `GLU_UNSIGNED_SHORT_5_6_5`, `GLU_UNSIGNED_SHORT_5_6_5_REV`, `GLU_UNSIGNED_SHORT_4_4_4_4`, `GLU_UNSIGNED_SHORT_4_4_4_4_REV`, `GLU_UNSIGNED_SHORT_5_5_5_1`, `GLU_UNSIGNED_SHORT_1_5_5_5_REV`, `GLU_UNSIGNED_INT_8_8_8_8`, `GLU_UNSIGNED_INT_8_8_8_8_REV`, `GLU_UNSIGNED_INT_10_10_10_2`, or `GLU_UNSIGNED_INT_2_10_10_10_REV`.

`dataIn`

  Specifies a pointer to the source image.

`wOut`
`hOut`

  Specify the width and height, respectively, in pixels of the destination image.

`typeOut`

  Specifies the data type for `dataOut`. Must be one of `GLU_UNSIGNED_BYTE`, `GLU_BYTE`, `GLU_BITMAP`, `GLU_UNSIGNED_SHORT`, `GLU_SHORT`, `GLU_UNSIGNED_INT`, `GLU_INT`, `GLU_FLOAT`, `GLU_UNSIGNED_BYTE_3_3_2`, `GLU_UNSIGNED_BYTE_2_3_3_REV`, `GLU_UNSIGNED_SHORT_5_6_5`, `GLU_UNSIGNED_SHORT_5_6_5_REV`, `GLU_UNSIGNED_SHORT_4_4_4_4`, `GLU_UNSIGNED_SHORT_4_4_4_4_REV`, `GLU_UNSIGNED_SHORT_5_5_5_1`, `GLU_UNSIGNED_SHORT_1_5_5_5_REV`, `GLU_UNSIGNED_INT_8_8_8_8`, `GLU_UNSIGNED_INT_8_8_8_8_REV`, `GLU_UNSIGNED_INT_10_10_10_2`, or `GLU_UNSIGNED_INT_2_10_10_10_REV`.

`dataOut`

  Specifies a pointer to the destination image.

## Description

`gluScaleImage` scales a pixel image using the appropriate pixel store modes to unpack data from the source image and pack data into the destination image.

When shrinking an image, `gluScaleImage` uses a box filter to sample the source image and create pixels for the destination image. When magnifying an image, the pixels from the source image are linearly interpolated to create the destination image.

A return value of zero indicates success, otherwise a GLU error code is returned (see gluErrorString).

See the glReadPixels reference page for a description of the acceptable values for the `format`, `typeIn`, and `typeOut` parameters.

## Notes

Formats `GLU_BGR`, and `GLU_BGRA`, and types `GLU_UNSIGNED_BYTE_3_3_2`, `GLU_UNSIGNED_BYTE_2_3_3_REV`, `GLU_UNSIGNED_SHORT_5_6_5`, `GLU_UNSIGNED_SHORT_5_6_5_REV`, `GLU_UNSIGNED_SHORT_4_4_4_4`, `GLU_UNSIGNED_SHORT_4_4_4_4_REV`, `GLU_UNSIGNED_SHORT_5_5_5_1`, `GLU_UNSIGNED_SHORT_1_5_5_5_REV`, `GLU_UNSIGNED_INT_8_8_8_8`, `GLU_UNSIGNED_INT_8_8_8_8_REV`, `GLU_UNSIGNED_INT_10_10_10_2`, and `GLU_UNSIGNED_INT_2_10_10_10_REV` are only available if the GL version is 1.2 or greater.

## Errors

`GLU_INVALID_VALUE` is returned if `wIn`, `hIn`, `wOut`, or `hOut` is negative.

`GLU_INVALID_ENUM` is returned if `format`, `typeIn`, or `typeOut` is not legal.

`GLU_INVALID_OPERATION` is returned if `typeIn` or `typeOut` is `GLU_UNSIGNED_BYTE_3_3_2` or `GLU_UNSIGNED_BYTE_2_3_3_REV` and `format` is not `GLU_RGB`.

`GLU_INVALID_OPERATION` is returned if `typeIn` or `typeOut` is `GLU_UNSIGNED_SHORT_5_6_5` or `GLU_UNSIGNED_SHORT_5_6_5_REV` and `format` is not `GLU_RGB`.

`GLU_INVALID_OPERATION` is returned if `typeIn` or `typeOut` is `GLU_UNSIGNED_SHORT_4_4_4_4` or `GLU_UNSIGNED_SHORT_4_4_4_4_REV` and `format` is neither `GLU_RGBA` nor `GLU_BGRA`.

`GLU_INVALID_OPERATION` is returned if `typeIn` or `typeOut` is `GLU_UNSIGNED_SHORT_5_5_5_1` or `GLU_UNSIGNED_SHORT_1_5_5_5_REV` and `format` is neither `GLU_RGBA` nor `GLU_BGRA`.

`GLU_INVALID_OPERATION` is returned if `typeIn` or `typeOut` is `GLU_UNSIGNED_INT_8_8_8_8` or `GLU_UNSIGNED_INT_8_8_8_8_REV` and `format` is neither `GLU_RGBA` nor `GLU_BGRA`.

`GLU_INVALID_OPERATION` is returned if `typeIn` or `typeOut` is `GLU_UNSIGNED_INT_10_10_10_2` or `GLU_UNSIGNED_INT_2_10_10_10_REV` and `format` is neither `GLU_RGBA` nor `GLU_BGRA`.

## See Also

gluBuild1DMipmaps, gluBuild2DMipmaps, gluBuild3DMipmaps, gluErrorString, glDrawPixels, glReadPixels

## Copyright

Copyright 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.