How to Use the 'magick convert' Command in ImageMagick 7+ (with Examples)

ImageMagick is a powerful and versatile software suite used for creating, editing, and converting bitmap images. In its latest versions (7+), the tool previously known as convert has been replaced by the magick convert command. This command provides a wealth of functionalities, such as converting between image formats, scaling images, creating GIFs, and constructing images from solid colors, among others. Below, we explore multiple use cases of magick convert, demonstrating its flexibility and efficiency.

Use case 1: Convert an image from JPEG to PNG

Code:

magick convert path/to/input_image.jpg path/to/output_image.png

Motivation:

Image format conversion is essential when working with diverse media platforms or software, especially when certain formats are required or preferred for specific processes. JPEG and PNG are widely used formats with differing advantages, such as JPEG’s compression capabilities and PNG’s support for transparency.

Explanation:

• magick convert: Invokes the convert function within ImageMagick’s command suite.
• path/to/input_image.jpg: Specifies the source image file in JPEG format.
• path/to/output_image.png: Determines the destination file to be saved in PNG format.

Example output:

A JPEG image named input_image.jpg is converted to a PNG image named output_image.png with no visible loss in quality, depending on the complexities and colors in the original image.

Use case 2: Scale an image to 50% of its original size

Code:

magick convert path/to/input_image.png -resize 50% path/to/output_image.png

Motivation:

Resizing images is a frequent task in graphic design, web development, and online publishing, where precise control over image dimensions impacts load times, aesthetics, and user experience. Scaling down images can reduce file size significantly, enhancing webpage performance or managing storage efficiently.

Explanation:

• magick convert: Utilizes ImageMagick’s conversion functionality.
• path/to/input_image.png: Denotes the source image to be resized.
• -resize 50%: Specifies that the image will be scaled to 50 percent of its original size, maintaining the aspect ratio.
• path/to/output_image.png: Points to the resized image to be saved as a new file.

Example output:

An image originally sized at 1000x800 pixels is resized to 500x400 pixels, producing output_image.png with approximately 50% of the original dimensions.

Use case 3: Scale an image keeping the original aspect ratio to a maximum dimension of 640x480

Code:

magick convert path/to/input_image.png -resize 640x480 path/to/output_image.png

Motivation:

Maintaining an image’s aspect ratio while resizing involves fitting within specific dimensions without distortion. This is crucial for ensuring content remains visually appealing across different devices and display sizes, crucial in web and app development.

Explanation:

• magick convert: Calls the conversion tool within ImageMagick.
• path/to/input_image.png: Designates the source image.
• -resize 640x480: Directs resizing according to the maximum boundaries of 640 pixels in width and 480 pixels in height, preserving aspect ratio.
• path/to/output_image.png: The output path for the resized image.

Example output:

An image initially 1920x1080 pixels is resized to 640x360 pixels to fit inside the specified 640x480 box, while keeping its original aspect ratio.

Use case 4: Scale an image to have a specified file size

Code:

magick convert path/to/input_image.png -define jpeg:extent=512kb path/to/output_image.jpg

Motivation:

Controlling the file size of images simplifies sharing and uploading, especially in environments with data limits or performance-conscious settings. This is particularly beneficial for optimizing websites and email attachments.

Explanation:

• magick convert: Starts ImageMagick’s conversion operation.
• path/to/input_image.png: Specifies the input image in PNG format.
• -define jpeg:extent=512kb: Indicates the target image should have a maximum file size of 512 kilobytes, utilizing JPEG compression methods.
• path/to/output_image.jpg: The converted output file path in JPEG format, adjusted to meet the specified size constraint.

Example output:

The original image is compressed to a JPEG output, output_image.jpg, with a file size adjusted to approximately 512 KB, making it ideal for uploading where size restrictions apply.

Use case 5: Vertically/horizontally append images

Code:

magick convert path/to/image1.png path/to/image2.png ... -append path/to/output_image.png

Motivation:

Appending images is useful for creating collages, comparison charts, or presentation slides where multiple images need to be displayed as a single unit without complex editing software. It streamlines the process of joining images cohesively.

Explanation:

• magick convert: Initiates ImageMagick’s conversion utility.
• path/to/image1.png path/to/image2.png ...: Lists images to be appended.
• -append: Concatenates images vertically. Use +append for horizontal concatenation.
• path/to/output_image.png: Specifies the file where the appended result is saved.

Example output:

Multiple images are joined seamlessly in a single file, either in a vertical stack via -append or side-by-side using +append, resulting in a unified visual as output_image.png.

Use case 6: Create a GIF from a series of images with 100ms delay between them

Code:

magick convert path/to/image1.png path/to/image2.png ... -delay 10 path/to/animation.gif

Motivation:

Animated GIFs bring static images to life, facilitating creative storytelling or visual instructions in a compact format. This is key in digital marketing, social media content, and tutorials.

Explanation:

• magick convert: Deploys ImageMagick’s capabilities in conversion.
• path/to/image1.png path/to/image2.png ...: A series of input images.
• -delay 10: Specifies a delay of 100 milliseconds (10x10 ms units) between frames.
• path/to/animation.gif: Outputs a GIF file, combining all input images with the specified delay setting.

Example output:

The resulting animation.gif loops through the input images, creating a seamless animated sequence appropriate for showcasing visual changes or animations in a compact file format.

Use case 7: Create an image with nothing but a solid red background

Code:

magick convert -size 800x600 "xc:#ff0000" path/to/image.png

Motivation:

Crafting images with solid backgrounds can serve as templates, digital art, or placeholders in design, making it easy to plan visual layouts or design elements.

Explanation:

• magick convert: Engages ImageMagick’s conversion suite.
• -size 800x600: Sets the dimensions of the resulting image.
• "xc:#ff0000": Utilizes a color expression (xc) to fill the image with red, denoted by its hex code #ff0000.
• path/to/image.png: Determines the output path for the created image file.

Example output:

An image dimensioned at 800x600 pixels, entirely red, is generated and saved as image.png, ready for insertion into design projects or as a solid backdrop.

Use case 8: Create a favicon from several images of different sizes

Code:

magick convert path/to/image1.png path/to/image2.png ... path/to/favicon.ico

Motivation:

Favicons are crucial for brand identity and user experience on websites, visible in browser tabs, address bars, and bookmarks. Combining multiple resolutions ensures compatibility across diverse devices and display settings.

Explanation:

• magick convert: Leverages ImageMagick’s conversion operations.
• path/to/image1.png path/to/image2.png ...: Includes variously sized images to be integrated into a single favicon.
• path/to/favicon.ico: Outputs the collection of images as an .ico file, standard for browser favicon usage.

Example output:

The generated favicon.ico merges multiple size variations to ensure that appropriate versions display clearly in different contexts, becoming an integral part of a brand’s digital identity.

Conclusion:

The magick convert command in ImageMagick 7+ proves to be an indispensable tool with its range of functionalities for anyone working with image manipulation. From basic format conversion and resizing to more complex tasks like creating GIFs and favicons, understanding these basic commands enables efficient and effective image processing tailored to specific needs and environments.