Open Source C Library to Create & Convert Images

Getting Started with ImageMagick

Clone the latest sources with using the following command

 git clone https://github.com/ImageMagick/ImageMagick.git 

$ rpm -Uvh ImageMagick-libs-7.0.10-60.x86_64.rpm 

Convert Image to Other Formats

The open source C library ImageMagick enables software programmers to convert images to other supported file formats inside their own apps. Users need to provide the format parameter before converting to another format. The library internally converts the image to other formats earlier, before applying the transformations. The library supports conversion to several popular image formats such as BMP, CMYK, GIF, JPEG, PBM, PNG, RGB, SVG, TIFF, and XPM formats. One great aspect of the library is the ease of use while converting the image. It also provides the ability to reduce the size of the image and apply different effects before writing it in the desired format.

#include  
using namespace std; 
using namespace Magick; 
int main(int argc,char **argv) 
{ 
  InitializeMagick(*argv);

  // Read GIF file from disk 
  Image image( "giraffe.gif" );
  // Write to BLOB in JPEG format 
  Blob blob; 
  image.magick( "JPEG" ) // Set JPEG output format 
  image.write( &blob );

  [ Use BLOB data (in JPEG format) here ]

  return 0; 
}

Image Gradients Support using C API

The open source C library ImageMagick enables software developers to create image gradients of multiple colors using C commands. You can easily create a gradual blend of one or multiple colors using horizontal, vertical, circular, or elliptical shapes. The library has enhanced the gradients through the use of several –defines such as specifying the direction of the linear gradient, Identifying coordinates of the center point for the radial gradient, Restricting the gradient to a larger or smaller region than the image dimensions, and so on. Moreover, for non-linear greyscale gradients, please add -colorspace RGB -colorspace gray before saving the output.

void test_wand(LPTSTR lpCmdLine)
{
	MagickWand *m_wand = NULL;
	PixelWand *p_wand = NULL;
	PixelIterator *iterator = NULL;
	PixelWand **pixels = NULL;
	int x,y,gray;
	char hex[128];

	MagickWandGenesis();

	p_wand = NewPixelWand();
	PixelSetColor(p_wand,"white");
	m_wand = NewMagickWand();
	// Create a 100x100 image with a default of white
	MagickNewImage(m_wand,100,100,p_wand);
	// Get a new pixel iterator 
	iterator=NewPixelIterator(m_wand);
	for(y=0;y<100;y++) {
		// Get the next row of the image as an array of PixelWands
		pixels=PixelGetNextIteratorRow(iterator,&x);
		// Set the row of wands to a simple gray scale gradient
		for(x=0;x<100;x++) {
			gray = x*255/100;
			sprintf(hex,"#%02x%02x%02x",gray,gray,gray);
			PixelSetColor(pixels[x],hex);
		}
		// Sync writes the pixels back to the m_wand
		PixelSyncIterator(iterator);
	}
	MagickWriteImage(m_wand,"bits_demo.gif");

	// Clean up
	iterator=DestroyPixelIterator(iterator);
	DestroyMagickWand(m_wand);
	MagickWandTerminus();

}

Apply Special Effects to Images via C

The open source C library ImageMagick has provided functionality for applying different types of effects to images. It has provided several important functions such as blurring, sharpening, threshold, creating shadows, feathering shapes, or tinting an image using a couple of lines of C code. There some special blur effects like radio blur and motion blur are also supported.

magick_wand = NewMagickWand();
	d_wand = NewDrawingWand();
	p_wand = NewPixelWand();

	set_tile_pattern(d_wand,"#check","pattern:checkerboard");

	PixelSetColor(p_wand,"lightblue");
	// Create a new transparent image
	MagickNewImage(magick_wand,320,100,p_wand);

	// Set up a 72 point font 
	DrawSetFont (d_wand, "Verdana-Bold-Italic" ) ;
	DrawSetFontSize(d_wand,72);
	// Now draw the text
	DrawAnnotation(d_wand,28,68,"Magick");
	// Draw the image on to the magick_wand
	MagickDrawImage(magick_wand,d_wand);
	// Trim the image
	MagickTrimImage(magick_wand,0);
	// Add a transparent border
	PixelSetColor(p_wand,"lightblue");
	MagickBorderImage(magick_wand,p_wand,5,5);
	// and write it
	MagickWriteImage(magick_wand,"text_pattern.png");

Large Images Support

The C library ImageMagick has provided support for working with very large images. It enables developers to open, read, process, or write images up to Mega-, Giga-, or Tera-pixel sizes inside their own image processing applications. The library allows resizing an image to a quarter million pixels square. While working with large images you need to make sure the availability of large memory resources. If the default temporary disk partition is small then guide ImageMagick to use another partition with a sufficient amount of free space.