# MagickCore, C API: Compute a Message Digest for an Image @ ImageMagick
ImageMagick® is a software suite to create, edit, compose, or convert bitmap images. It can read and write images in a variety of formats (over 200) including PNG, JPEG, JPEG-2000, GIF, WebP, Postscript, PDF, and SVG. Use ImageMagick to resize, flip, mirror, rotate, distort, shear and transform images, adjust image colors, apply various special effects, or draw text, lines, polygons, ellipses and Bézier curves.
Author: ImageMagick Studio LLC
Keywords: magickcore, c, api:, compute, a, message, digest, for, an, image, ImageMagick, PerlMagick, image processing, image, photo, software, Magick++, OpenMP, convert

SignatureImage

## SignatureImage

SignatureImage() computes a message digest from an image pixel stream with an implementation of the NIST SHA-256 Message Digest algorithm. This signature uniquely identifies the image and is convenient for determining if an image has been modified or whether two images are identical.

The format of the SignatureImage method is:

    MagickBooleanType SignatureImage(Image *image,ExceptionInfo *exception)

A description of each parameter follows:

image
  the image.
exception
  return any errors or warnings in this structure.