How to Add Text to PPM Images Using ppmlabel (with examples)

The ppmlabel command is a part of the Netpbm library, a package of graphics programs and a programming library. It is used to overlay text on portable pixmap (PPM) images, enabling users to add annotations, labels, or other text information directly onto an image. This command allows for customization of the text position, color, size, and rotation, providing flexibility for various image processing needs.

Use case 1: Add text to a PPM image at the specified location

Code:

ppmlabel -x 100 -y 150 -text "Hello World" path/to/input_file.ppm > path/to/output_file.ppm

Motivation:

In many instances, you may need to annotate an image with specific text for identification purposes, such as marking a date on a photo or adding a watermark. This command provides a straightforward way to do so. It allows placing the text precisely where needed, enhancing the image’s informational value without altering the overall design significantly.

Explanation:

• -x 100 -y 150: These arguments specify the coordinates for the text on the image. Here, the text “Hello World” will be placed 100 pixels from the left edge and 150 pixels from the top of the image. It provides the flexibility to position the text exactly where it needs to be.
• -text "Hello World": This argument defines the text string that will be applied to the image.
• path/to/input_file.ppm: This is the path to the input PPM image file that the text will be added to.
• > path/to/output_file.ppm: This redirects the output to a new file, allowing you to maintain the original image without alterations.

Example output:

You start with an image of a serene landscape and overlay the text “Hello World” at a location that does not detract from the scene’s natural beauty. The output file now features this text, clearly visible at the specified coordinates.

Use case 2: Add multiple texts at different locations

Code:

ppmlabel -x 50 -y 100 -text "Title: Sunset" -x 200 -y 300 -text "Location: Beach" path/to/input_file.ppm > path/to/output_file.ppm

Motivation:

Sometimes, adding multiple annotations on an image enhances the value. For instance, if you are creating a photo album or documentation, you might want to label different parts of the image with distinct pieces of information like titles, locations, or dates. This command allows you to place multiple text strings on the image, each at a different position, creating a rich contextual backdrop against the visual content.

Explanation:

• -x 50 -y 100 -text "Title: Sunset": Specifies the position (50, 100) and text (“Title: Sunset”) for the first label.
• -x 200 -y 300 -text "Location: Beach": Specifies a different position (200, 300) and text (“Location: Beach”) for the second label.
• path/to/input_file.ppm: The path to the source image.
• > path/to/output_file.ppm: Directs the resulting image to a new file to preserve the original.

Example output:

An image of a sunset over a beach is annotated with the title “Title: Sunset” and a location note “Location: Beach,” positioned strategically on the image not to obscure key visual elements. The output file now contains both annotations, adding narrative context to the image.

Use case 3: Specify the line color, the background color, the tilt, and the size of the added text

Code:

ppmlabel -x 120 -y 200 -color red -background yellow -angle 45 -size 20 -text "Sample Text" path/to/input_file.ppm > path/to/output_file.ppm

Motivation:

For a more aesthetic touch, especially when preparing images for presentations or publications, customizing text visuals is crucial. Adjusting the text’s color, background, angle, and size allows you to align with the overall design theme, improving readability and visual appeal. This command variation permits complete control over the appearance of the text annotations.

Explanation:

• -x 120 -y 200: Determines where the text will be placed in the image, precisely 120 pixels from the left and 200 pixels from the top.
• -color red: Sets the color of the text to red, ensuring it stands out against the background.
• -background yellow: Sets a yellow background for the text, enhancing visibility even more.
• -angle 45: Rotates the text by 45 degrees, which can add a dynamic element to the presentation.
• -size 20: Adjusts the font size to 20, easily readable from a distance.
• -text "Sample Text": The actual text string to be displayed.
• path/to/input_file.ppm: Specifies the source PPM image.
• > path/to/output_file.ppm: Ensures the changes are directed to a separate file, preserving the original image file.

Example output:

You have an image where readability might be challenging due to busy backgrounds. Using ppmlabel, you overlay “Sample Text” in a dynamic red font against a yellow backdrop at a 45-degree angle, effectively maintaining visibility and contributing a creative flair. The output image integrates this visually distinct text seamlessly.

Conclusion:

The ppmlabel command from the Netpbm package provides a plethora of options for integrating text into PPM images, offering extensive customization in terms of positioning, color, and font attributes. Each use case explained demonstrates the command’s utility in different contexts, from simple annotations to detailed stylistic edits, enhancing the usability and presentation of images for a variety of purposes.