blur-and-sharpen.md

Blur and Sharpen effects

Skymage offers two powerful image enhancement effects: Blur and Sharpen. These effects can be applied through simple parameters to create various visual styles and improve image quality.

Blur

The blur effect softens your images, creating a more diffuse, dreamy aesthetic.

Basic Blur Usage

To apply a blur effect, add the blur parameter to your image URL:

https://demo.skymage.net/v1/daudau.cc/images/crab.png?blur=5

Blur Intensity

The blur parameter accepts values between 0.3 and 1000, representing the blur radius:

• Lower values (0.3-3): Subtle blur effect
• Medium values (3-10): Moderate blur
• Higher values (10+): Strong blur effect

Blur Examples

Subtle Blur (blur=1):

https://demo.skymage.net/v1/daudau.cc/images/crab.png?blur=1

Moderate Blur (blur=5):

https://demo.skymage.net/v1/daudau.cc/images/crab.png?blur=5

Strong Blur (blur=20):

https://demo.skymage.net/v1/daudau.cc/images/crab.png?blur=20

Blur Implementation Details

When you specify a value between 0.3 and 1000, Skymage applies a Gaussian blur with the specified sigma value. For values outside this range or non-numeric values, a fast, mild blur is applied using a 3×3 averaging filter.

Common Blur Use Cases

• Background Blur: Blur images used as backgrounds to make foreground content more readable
• Privacy: Blur portions of an image to hide sensitive information
• Focus Effect: Blur the background to emphasize the main subject
• Thumbnail Previews: Use blur for low-quality image placeholders while full images load

Sharpen

The sharpen effect enhances image details and increases perceived clarity. This is particularly useful for images that appear slightly blurry or lack definition.

Basic Sharpen Usage

To sharpen an image, add the sharp parameter to your image URL:

https://demo.skymage.net/v1/daudau.cc/images/crab.png?sharp=5

Sharpening Intensity

The sharp parameter accepts values between 0 and 10, where:

• Lower values (1-3): Subtle sharpening
• Medium values (4-6): Moderate sharpening
• Higher values (7-10): Strong sharpening

Sharpen Examples

Subtle Sharpening (sharp=2):

https://demo.skymage.net/v1/daudau.cc/images/crab.png?sharp=2

Moderate Sharpening (sharp=5):

https://demo.skymage.net/v1/daudau.cc/images/crab.png?sharp=5

Strong Sharpening (sharp=9):

https://demo.skymage.net/v1/daudau.cc/images/crab.png?sharp=9

Sharpen Implementation Details

Skymage's sharpening algorithm intelligently adapts to different areas of the image:

• Flat Areas: Applies gentler sharpening to avoid introducing noise
• Jagged Areas: Applies stronger sharpening to enhance details

The sharpening process works in LAB color space to minimize color distortion while maximizing detail enhancement.

Common Sharpen Use Cases

• Enhance Product Photos: Make product details more visible
• Improve Text Legibility: Sharpen images containing text
• Rescue Slightly Blurry Images: Add clarity to images that aren't perfectly focused
• Enhance Architectural Details: Bring out textures and patterns in buildings
• Improve After Resizing: Restore detail lost during downsizing

Combining with Other Parameters

Both effects work well in combination with other transformations:

Blur with Resize:

https://demo.skymage.net/v1/daudau.cc/images/crab.png?w=300&blur=3

Sharpen with Resize:

https://demo.skymage.net/v1/daudau.cc/images/crab.png?w=300&sharp=4

Format Conversion:

https://demo.skymage.net/v1/daudau.cc/images/crab.png?blur=5&f=webp

Performance Best Practices

• Higher blur values and stronger sharpening require more processing time
• Apply these effects after resizing for better performance
• Subtle effects often provide the best balance between visual improvement and processing efficiency
• For time-sensitive applications, use modest enhancement values
• Consider the content: portraits typically need less sharpening than landscapes or product photos