ImgCap

Automatically compress images to approximate target file size using binary search algorithm.

   

``shell
$ pnpm install imgcap
`

View Demo

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Modern applications should handle image size constraints transparently, creating seamless user interactions. imgcap implements intelligent auto-compression that respects file size limits while maintaining optimal image quality - enabling fluid, friction-free upload experiences that follow good human-computer interaction principles.

Note: The targetSize represents an ideal target. The actual output size will approximate this value within a reasonable tolerance range for optimal performance.

`typescript
// Before: User sees error, leaves frustrated
❌ "File too large: Image upload size cannot exceed 2MB"

// After: Seamless auto-compression
✅ await imgcap(userPhoto, { targetSize: 2 1024 1024 })
`

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`typescript
import imgcap from 'imgcap'

// Social media avatar (500KB limit)
const avatar = await imgcap(file, { targetSize: 500 * 1024 })

// With format conversion
const webp = await imgcap(imageFile, {
targetSize: 300 * 1024,
outputType: 'image/webp'
})
`

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`typescript
interface Options {
targetSize: number // Target file size in bytes (approximate)
outputType?: ImageType // Output format (default: same as input)
}

type ImageType = 'image/jpeg' | 'image/png' | 'image/webp' | 'image/avif'
``

#### Tolerance Behavior

The algorithm automatically applies smart tolerance based on target size:

- Small files (<100KB): ±1KB tolerance for high precision
- Medium files (100KB-100MB): ±1% tolerance for reasonable flexibility
- Large files (>100MB): ±1MB tolerance to avoid excessive processing

Examples:

- Target 50KB → Actual: 49-51KB
- Target 500KB → Actual: 495-505KB
- Target 50MB → Actual: 49.5-50.5MB
- Target 1GB → Actual: 1023-1025MB

Browser only - Requires OffscreenCanvas support (modern browsers).

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MIT © molvqingtai