Image processing and GD functions in PHP let you create and edit images in
formats like GIF, PNG, JPEG, WBMP, and XPM. PHP can send the image directly to
the browser. These functions need certain libraries, depending on the image
format you use.
Example: Using `imagecolorclosesthwb()` in PHP
Here’s an example of how to use the `imagecolorclosesthwb()` function in PHP.
<?php
// Create new image from given URL
$image = imagecreatefromgif(
'https://media.geeksforgeeks.org/wp-content/uploads/animateImages.gif');
// Display the index of color
echo 'Hue White and Blackness closest color index: '
. imagecolorclosesthwb($image, 5, 165, 10);
imagedestroy($image);
?>
Output:
Hue White and Blackness closest color index: 42
This code creates an image from a GIF URL and finds the closest color index
using the `imagecolorclosesthwb()` function.
The list of Image processing and GD s are given below:
| GD Functions | Description |
|---|---|
| gd_info() | Retrieve information about the currently installed GD library. |
| getimagesize() | Get the size (width and height) of an image. |
| getimagesizefromstring() | Get the size (width and height) of an image from a string containing the image data. |
| imagealphablending() | Set the blending mode for an image, affecting how colors are combined during drawing operations. |
| imagearc() | Create an arc of a circle centered at the given coordinates. |
| imagechar() | Draw a single character horizontally at the specified coordinates. |
| imagecharup() | Draw a single character vertically at the specified coordinates. |
| imagecolorallocate() | Allocate a color for an image. This function assigns a new color to the color palette and returns the index of that color. |
| imagecolorallocatealpha() | Allocate a color with an alpha transparency value for an image. |
| imagecolorat() | Get the index of the color of the pixel at a specified coordinate in the image. |
| imagecolorclosest() | Get the index of the color in the image's palette that is closest to the specified color. |
| imagecolorclosestalpha() | Get the index of the color in the image's palette that is closest to the specified color, considering both color and alpha values. |
| imagecolorclosesthwb() | Get the index of the color in the image's palette that is closest to the specified color in terms of Hue, Whiteness, and Blackness values. |
| imagecolorexact() | Get the index of the specified color in the palette of the image, if it exists. |
| imagecolormatch() | Reduce the number of colors in an image's palette while attempting to match the colors of the original image as closely as possible. |
| imagecolorresolve() | Attempts to find a close match for a specified color within the image's palette and returns the index of that color. |
| imagecolorresolvealpha() | Attempts to find a close match for a specified color with an alpha transparency value within the image's palette and returns the index of that color. |
| imagecolorset() | Set the red, green, and blue components of a color in the image's palette at a specified index. |
| imagecolorsforindex() | Get the red, green, blue, alpha (if applicable), and exact color value (represented as a string) for a color at a specified index in the image's palette. |
| imagecolorstotal() | Find the number of colors currently in an image's palette. |
| imagecolortransparent() | Define a specific color in the image's palette as transparent. |
| imageconvolution() | Apply a convolution filter to the image to modify the image content (e.g., blurring, sharpening). |
| imagecopy() | Copy all or a portion of one image onto another image. |
| imagecopymerge() | Copy an image or a portion of an image onto another image and merge the colors using the specified alpha transparency value. |
| imagecopymergegray() | Copy an image or a portion of an image with a grayscale effect onto another image and merge the colors using the specified alpha transparency value. |
| imagecreate() | Create a new image of a specified width and height. |
| imagecreatetruecolor() | Create a new true-color image of a specified width and height. True-color images allow for millions of colors, while images created with `imagecreate()` are limited to a 256-color palette. |
| imagecrop() | Crop an image to a rectangular region defined by coordinates. |
| imagedashedline() | Draw a dashed line between two coordinates using a specified pattern. |
| imagefill() | Fill the entire image with a specified color. |
| imagefilledarc() | Draws a filled arc centered at the specified coordinate with a starting and ending angle. |
| imagefilledellipse() | Draw a filled ellipse at the specified coordinates. |
| imagefilledrectangle() | Draw a filled rectangle with specified coordinates for the top-left and bottom-right corners. |
| imageflip() | Flip an image horizontally, vertically, or both. |
| imagegif() | Output the image to a GIF file. |
| imagelayereffect() | Enable or disable alpha blending, which allows for layering effects where translucent colors are combined. |
| imagepolygon() | Draw a polygon (closed shape) with a specified array of coordinates for its vertices. |
| imagerectangle() | Draw a rectangle with specified coordinates for the top-left and bottom-right corners. |
| imagetruecolortopalette() | Convert a true-color image to a palette image (limited to 256 colors). |
| imagesetthickness() | Set the thickness of lines drawn with subsequent drawing functions. |
| imagesettile() | Set a tile image to be used for filling areas. The tile image will be repeated to fill the specified area. |
| imagestringup() | Draw a string of characters vertically at the specified coordinates. |
| imagesx() | Return the width of the given image. |
| imagesy() | Return the height of the given image. |