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Image Functions Using the GD Library

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GD Library Function Reference

The "GD Library" is the most used image-processing tool in PHP, allowing the dynamic creation and editing of images, charts, thumbnails, etc.

The file types that can be created and/or edited using the GD library are GIF, JPEG and PNG.

The GD library will be included with most PHP installations. To confirm if the GD library is activated on your server/host, you can run <?php echo phpinfo(); ?> and scroll down to "GD" to confirm its status.

The GD library includes over 100 functions:

Function Description
gd_info Retrieve information about the currently installed GD library
getimagesize Get the size of an image
image_type_to_extension Get file extension for image type
image_type_to_mime_type Get Mime-Type for image-type returned by getimagesize, exif_read_data, exif_thumbnail, exif_imagetype
image2wbmp Output image to browser or file
imagealphablending Set the blending mode for an image
imageantialias Should antialias functions be used or not
imagearc Draws an arc
imagechar Draw a character horizontally
imagecharup Draw a character vertically
imagecolorallocate Allocate a color for an image
imagecolorallocatealpha Allocate a color for an image
imagecolorat Get the index of the color of a pixel
imagecolorclosest Get the index of the closest color to the specified color
imagecolorclosestalpha Get the index of the closest color to the specified color + alpha
imagecolorclosesthwb Get the index of the color which has the hue, white and blackness
imagecolordeallocate De-allocate a color for an image
imagecolorexact Get the index of the specified color
imagecolorexactalpha Get the index of the specified color + alpha
imagecolormatch Makes the colors of the palette version of an image more closely match the true color version
imagecolorresolve Get the index of the specified color or its closest possible alternative
imagecolorresolvealpha Get the index of the specified color + alpha or its closest possible alternative
imagecolorset Set the color for the specified palette index
imagecolorsforindex Get the colors for an index
imagecolorstotal Find out the number of colors in an image's palette
imagecolortransparent Define a color as transparent
imageconvolution Apply a 3x3 convolution matrix, using coefficient and offset
imagecopy Copy part of an image
imagecopymerge Copy and merge part of an image
imagecopymergegray Copy and merge part of an image with gray scale
imagecopyresampled Copy and resize part of an image with resampling
imagecopyresized Copy and resize part of an image
imagecreate Create a new palette based image
imagecreatefromgd2 Create a new image from GD2 file or URL
imagecreatefromgd2part Create a new image from a given part of GD2 file or URL
imagecreatefromgd Create a new image from GD file or URL
imagecreatefromgif Create a new image from file or URL
imagecreatefromjpeg Create a new image from file or URL
imagecreatefrompng Create a new image from file or URL
imagecreatefromstring Create a new image from the image stream in the string
imagecreatefromwbmp Create a new image from file or URL
imagecreatefromxbm Create a new image from file or URL
imagecreatefromxpm Create a new image from file or URL
imagecreatetruecolor Create a new true color image
imagedashedline Draw a dashed line
imagedestroy Destroy an image
imageellipse Draw an ellipse
imagefill Flood fill
imagefilledarc Draw a partial arc and fill it
imagefilledellipse Draw a filled ellipse
imagefilledpolygon Draw a filled polygon
imagefilledrectangle Draw a filled rectangle
imagefilltoborder Flood fill to specific color
imagefilter Applies a filter to an image
imagefontheight Get font height
imagefontwidth Get font width
imageftbbox Give the bounding box of a text using fonts via freetype2
imagefttext Write text to the image using fonts using FreeType 2
imagegammacorrect Apply a gamma correction to a GD image
imagegd2 Output GD2 image to browser or file
imagegd Output GD image to browser or file
imagegif Output image to browser or file
imagegrabscreen Captures the whole screen
imagegrabwindow Captures a window
imageinterlace Enable or disable interlace
imageistruecolor Finds whether an image is a truecolor image
imagejpeg Output image to browser or file
imagelayereffect Set the alpha blending flag to use the bundled libgd layering effects
imageline Draw a line
imageloadfont Load a new font
imagepalettecopy Copy the palette from one image to another
imagepng Output a PNG image to either the browser or a file
imagepolygon Draws a polygon
imagepsbbox Give the bounding box of a text rectangle using PostScript Type1 fonts
imagepsencodefont Change the character encoding vector of a font
imagepsextendfont Extend or condense a font
imagepsfreefont Free memory used by a PostScript Type 1 font
imagepsloadfont Load a PostScript Type 1 font from file
imagepsslantfont Slant a font
imagepstext Draws a text over an image using PostScript Type1 fonts
imagerectangle Draw a rectangle
imagerotate Rotate an image with a given angle
imagesavealpha Set the flag to save full alpha channel information (as opposed to single-color transparency) when saving PNG images
imagesetbrush Set the brush image for line drawing
imagesetpixel Set a single pixel
imagesetstyle Set the style for line drawing
imagesetthickness Set the thickness for line drawing
imagesettile Set the tile image for filling
imagestring Draw a string horizontally
imagestringup Draw a string vertically
imagesx Get image width
imagesy Get image height
imagetruecolortopalette Convert a true color image to a palette image
imagettfbbox Give the bounding box of a text using TrueType fonts
imagettftext Write text to the image using TrueType fonts
imagetypes Return the image types supported by this PHP build
imagewbmp Output image to browser or file
imagexbm Output XBM image to browser or file
iptcembed Embeds binary IPTC data into a JPEG image
iptcparse Parse a binary IPTC block into single tags.
jpeg2wbmp Convert JPEG image file to WBMP image file
png2wbmp Convert PNG image file to WBMP image file

We will learn about some of the more interesting functions over the course of the next few pages.