Image types¶
Every raster image in gfx-php implements the RasterImage interface.
There are several classes that implement this interface, which handle different representations of the image data.
RgbRasterImage- Holds RGB data.
GrayscaleRasterImage- Holds monochrome data.
BlackAndWhiteRasterImage- Holds 1-bit raster data.
IndexedRasterImage- Holds an image and associated palette.
Creating an image¶
Each of these classes has a static method which can be used to create an image of that type.
These only require a width and height.
use Mike42\GfxPhp\BlackAndWhiteRasterImage;
$image = BlackAndWhiteRasterImage::create(50, 100);
Converting between image types¶
You can convert between image types. This is similar to performing a color-space conversion in an image editor.
use Mike42\GfxPhp\Image;
$image = Image::load("tux.ppm");
$image -> toBlackAndWhite();
The methods to use are:
RasterImage::toBlackAndWhite()RasterImage::toGrayscale()RasterImage::toIndexed()RasterImage::toRgb()
Each of these returns an image of the requested type. They work by instantiating a new image, then copying across the data as accurately as possible. As a result, the original image is unmodified.
Implicit conversions¶
Some file formats only accept specific types of raster data, so the RasterImage::write() method will need to convert it. For example, this .pbm will be limited to 2 colors, which is achieved by using RasterImage:toBlackAndWhite in the background:
use Mike42\GfxPhp\Image;
$wheel = Image::load("colorwheel.ppm");
$wheel -> write("wheel.pbm");
Since converting the color space creates a new image, the image stored in $wheel is unmodified.