The result is not the same as the original js lib

[davyzhang]

Thank you for maintaining this wonderful port from js lib

However I found the result sometimes is not the same as the original one. Not only the part of the image, but also the size of image is 512x512, even I use 300x300 in code.

package main

import (
	"fmt"
	"image"
	"image/jpeg"
	"math"
	"os"

	"github.com/muesli/smartcrop"
	"github.com/muesli/smartcrop/nfnt"

)

func main() {
	f, _ := os.Open("/tmp/origin.jpeg")
	img, _, _ := image.Decode(f)

	analyzer := smartcrop.NewAnalyzer(nfnt.NewDefaultResizer())
	topCrop, _ := analyzer.FindBestCrop(img, 300, 300)

	// The crop will have the requested aspect ratio, but you need to copy/scale it yourself
	fmt.Printf("Top crop: %+v\n", topCrop)

	type SubImager interface {
		SubImage(r image.Rectangle) image.Image
	}
	croppedimg := img.(SubImager).SubImage(topCrop)

	//save cropped image to file out.png
	// Save cropped image to file
	out, err := os.Create("/tmp/cropped.jpeg")
	if err != nil {
		fmt.Println("Failed to create the file:", err)
		return
	}
	defer out.Close()

	// Choose quality of the jpeg (1-100), higher is better quality
	err = jpeg.Encode(out, croppedimg, &jpeg.Options{Quality: 90})
	if err != nil {
		fmt.Println("Failed to save the image:", err)
		return
	}
	fmt.Println("Cropped image saved to /tmp/cropped.jpeg")
}

oringal image

cropped use js version

cropped use this lib

[davyzhang]

If I resize the image proportionally before crop it, the result is better but still not the same as the original one

package main

import (
	"fmt"
	"image"
	"image/jpeg"
	"math"
	"os"

	"github.com/muesli/smartcrop"
	"github.com/muesli/smartcrop/nfnt"
	"github.com/nfnt/resize"
)

func main() {
	f, _ := os.Open("/tmp/origin.jpeg")
	img, _, _ := image.Decode(f)

	img = resizeImage(img, 300, 300)

	analyzer := smartcrop.NewAnalyzer(nfnt.NewDefaultResizer())
	topCrop, _ := analyzer.FindBestCrop(img, 300, 300)

	// The crop will have the requested aspect ratio, but you need to copy/scale it yourself
	fmt.Printf("Top crop: %+v\n", topCrop)

	type SubImager interface {
		SubImage(r image.Rectangle) image.Image
	}
	croppedimg := img.(SubImager).SubImage(topCrop)

	//save cropped image to file out.png
	// Save cropped image to file
	out, err := os.Create("/tmp/cropped.jpeg")
	if err != nil {
		fmt.Println("Failed to create the file:", err)
		return
	}
	defer out.Close()

	// Choose quality of the jpeg (1-100), higher is better quality
	err = jpeg.Encode(out, croppedimg, &jpeg.Options{Quality: 90})
	if err != nil {
		fmt.Println("Failed to save the image:", err)
		return
	}
	fmt.Println("Cropped image saved to /tmp/cropped.jpeg")
}

func resizeImage(img image.Image, targetWidth, targetHeight uint) image.Image {
	// Calculate the scaling factor and dimensions for resizing
	originalBounds := img.Bounds()
	originalWidth := originalBounds.Dx()
	originalHeight := originalBounds.Dy()

	var scalingFactor float64
	if originalWidth < originalHeight {
		scalingFactor = float64(targetWidth) / float64(originalWidth)
	} else {
		scalingFactor = float64(targetHeight) / float64(originalHeight)
	}

	newWidth := uint(math.Round(float64(originalWidth) * scalingFactor))
	newHeight := uint(math.Round(float64(originalHeight) * scalingFactor))

	// Resize the image with the new dimensions
	resizedImg := resize.Resize(newWidth, newHeight, img, resize.Lanczos3)

	return resizedImg
}