Bez popisu

1 Větve

Dobrosław Żybort b744503c5c Add: thumbnail helper function		před 12 roky
.travis.yml	09f4012229 Add Travis integration	před 13 roky
LICENSE	fa6861a5fd Documentation updated	před 13 roky
README.md	4d25061069 Fixed yet another typo.	před 12 roky
converter.go	a32116ce4a Add documentation	před 13 roky
filters.go	494d8de4e5 Speedup calculation by exploiting the separability of the resizing filter.	před 12 roky
resize.go	f8ec710330 Fix wrong calculation of second adjust parameter.	před 12 roky
resize_test.go	252ccc84a2 Add benchmarks for Lanczos3Lut to compare it with Lanczos3 performance.	před 12 roky
sinc.go	428642c9f1 initial commit	před 13 roky
sinc_test.go	428642c9f1 initial commit	před 13 roky
thumbnail.go	b744503c5c Add: thumbnail helper function	před 12 roky
thumbnail_test.go	b744503c5c Add: thumbnail helper function	před 12 roky

Resize

Image resizing for the Go programming language with common interpolation methods.

Installation

$ go get github.com/nfnt/resize

It's that easy!

Usage

Import package with

import "github.com/nfnt/resize"

Resize creates a scaled image with new dimensions (width, height) using the interpolation function interp. If either width or height is set to 0, it will be set to an aspect ratio preserving value.

resize.Resize(width, height uint, img image.Image, interp resize.InterpolationFunction) image.Image

The provided interpolation functions are (from fast to slow execution time)

NearestNeighbor: Nearest-neighbor interpolation
Bilinear: Bilinear interpolation
Bicubic: Bicubic interpolation
MitchellNetravali: Mitchell-Netravali interpolation
Lanczos2Lut: Lanczos resampling with a=2 using a look-up table for fast computation
Lanczos2: Lanczos resampling with a=2
Lanczos3Lut: Lanczos resampling with a=3 using a look-up table for fast computation
Lanczos3: Lanczos resampling with a=3

Which of these methods gives the best results depends on your use case.

Sample usage:

package main

import (
	"github.com/nfnt/resize"
	"image/jpeg"
	"log"
	"os"
)

func main() {
	// open "test.jpg"
	file, err := os.Open("test.jpg")
	if err != nil {
		log.Fatal(err)
	}

	// decode jpeg into image.Image
	img, err := jpeg.Decode(file)
	if err != nil {
		log.Fatal(err)
	}
	file.Close()

	// resize to width 1000 using Lanczos resampling
	// and preserve aspect ratio
	m := resize.Resize(1000, 0, img, resize.Lanczos3)

	out, err := os.Create("test_resized.jpg")
	if err != nil {
		log.Fatal(err)
	}
	defer out.Close()

	// write new image to file
	jpeg.Encode(out, m, nil)
}

Downsizing Samples

Downsizing is not as simple as it might look like. Images have to be filtered before they are scaled down, otherwise aliasing might occur. Filtering is highly subjective: Applying too much will blur the whole image, too little will make aliasing become apparent. Resize tries to provide sane defaults that should suffice in most cases.