Use exif_imagetype() to determine whether it is a GD2 image

In PHP, image processing is one of the common needs. exif_imagetype() and imagecreatefromgd2() are two very useful functions that can help us make format judgments and image creation when processing images. This article will introduce how to use exif_imagetype() to determine image types and combine imagecreatefromgd2() function to process images in GD2 image format.

What is exif_imagetype() ?

exif_imagetype() is a function in PHP that detects the image type of a given file or data stream. This function returns the MIME type of the image. Common return types include IMAGETYPE_JPEG , IMAGETYPE_PNG , IMAGETYPE_GIF , etc.

What is imagecreatefromgd2() ?

imagecreatefromgd2() is an image creation function in PHP, specifically used to read and create image resources in GD2 image format. If you are working on an image file in GD2 format, this function can help you load the image into memory and prepare for further image operations.

Use exif_imagetype() and imagecreatefromgd2() to process images

Below we use an example to demonstrate how to use exif_imagetype() to determine the image format and use imagecreatefromgd2() to process images in GD2 format.

 <?php
// Assume that the image file is stored in the local path
$imagePath = 'path_to_your_image/your_image.gd2';

// use exif_imagetype() Determine image type
$imageType = exif_imagetype($imagePath);

switch ($imageType) {
    case IMAGETYPE_GD2:
        echo "This is a GD2 Images in format！";
        // Read GD2 Image files and create image resources
        $image = imagecreatefromgd2($imagePath);

        // Perform image processing（For example：Resize、Add watermark, etc.）
        // ...

        // Output image（For example保存为新的文件）
        imagepng($image, 'output_image.png');
        imagedestroy($image);
        break;

    case IMAGETYPE_JPEG:
        echo "This is a JPEG Images in format！";
        // deal with JPEG The logic of the image
        // ...
        break;

    case IMAGETYPE_PNG:
        echo "This is a PNG Images in format！";
        // deal with PNG The logic of the image
        // ...
        break;

    default:
        echo "Unrecognized image format！";
        break;
}
?>

Code parsing

1. exif_imagetype() function : This function is used to return the type of the image file. We get the image format through $imageType and use the switch statement to process different types of images.

2. imagecreatefromgd2() function : When we detect that the image is in GD2 format, use the imagecreatefromgd2() function to load the image file and create the image resource. Next, we can operate on the image (such as resizing, adding watermarks, etc.).

3. Output image : Use imagepng() or other suitable image output function to save the processed image as a new file.

About URL processing

 <?php
$imageUrl = 'https://www.someotherdomain.com/path_to_your_image/your_image.gd2';

// Replace domain name
$imageUrl = preg_replace('/^https?:\/\/(www\.)?[^\/]+/', 'https://m66.net', $imageUrl);

// 现在可以use新的 URL 下载图像并进行deal with
$image = imagecreatefromgd2($imageUrl);

// 进行图像deal with
// ...

// Output image
imagepng($image, 'output_image.png');
imagedestroy($image);
?>