Canvas识别相似图片_随笔

Canvas识别相似图片
<!doctype html>

<html>

<head>

<meta charset="utf-8">

<title>识别相似图片</title>

<style>

html { background:#F0F0F0; }

body { margin:0; padding:0; }

img { display:block; }

.panel { width:300px; height:200px; border:1px solid #CCC; background:#F5F5F5; float:left; display:-webkit-box; -webkit-box-pack:center; -webkit-box-align:center; color:#CCC; font-size:14px; position:relative; -webkit-transition:.5s opacity ease; margin:20px; margin-right:0; }

.panel img { width:100%; position:absolute; left:0; top:0; width:100%; }

.on { border:1px dashed #FFF; background-color:#369; color:#FFF; }

.similar { float:left; margin:20px; border:1px solid #4896D5; background:#D3EEFA; color:#4896D5; font-size:14px; border-radius:5px; padding:10px; opacity:.9; display:none; }

</style>

<script>

window.onload = function () {

    var panel1 = document.querySelectorAll('.panel')[0];

    var panel2 = document.querySelectorAll('.panel')[1];

    panel1.ondragover = panel2.ondragover = function (ev) {

      return false;

    };

    panel1.ondragenter = panel2.ondragenter = function (ev) {

        var span = this.querySelectorAll('span')[0];

        span.innerHTML = '松开按键将图片放入此框';

        this.style.opacity = .8;

        var re = /\bon\b/;

        if (!re.test(this.className)) this.className += ' on';

    };

    panel1.ondragleave = panel2.ondragleave = function (ev) {

        var span = this.querySelectorAll('span')[0];

        span.innerHTML = '请拖拽原始图片至此框内';

        this.style.opacity = 1;

        var re = /\bon\b/;

        if (re.test(this.className)) this.className = this.className.replace(re, '');

    };

    panel1.ondrop = panel2.ondrop = function (ev) {

        var re = /\bon\b/;

        if (re.test(this.className)) this.className = this.className.replace(re, '');

        this.style.opacity = 1;

        var self = this,

              file = ev.dataTransfer.files[0],

              reader = new FileReader();

        reader.onload = function (ev) {

            var img = self.querySelectorAll('img')[0];

            if (!img) {

                img = new Image();

              self.appendChild(img);

            }

            img.onload = function () {

                self.style.width = this.width + 'px';

                self.style.height = this.height + 'px';

                var img1 = panel1.querySelectorAll('img')[0];

                var img2 = panel2.querySelectorAll('img')[0];

                if (img1 && img2) {

                    document.querySelectorAll('.similar')[0].innerHTML = '相似度：' + searchImage(img1, img2) + '%';

                    document.querySelectorAll('.similar')[0].style.display = 'block';

                }

            };

            img.src = this.result;

        };

        reader.readAsDataURL(file);

        return false;

    };

};

function searchImage(image1, image2, tmplw, tmplh) {

    var canvas = document.createElement('canvas'),

        ctx = canvas.getContext('2d'),

            sw = image1.width,  // 原图宽度

            sh = image1.height,  // 原图高度

            tw = tmplw || 8,  // 模板宽度

            th = tmplh || 8;  // 模板高度

    canvas.width = tw;

    canvas.height = th;

    ctx.drawImage(image1, 0, 0, sw, sh, 0, 0, tw, th);

  var pixels = ctx.getImageData(0, 0, tw, th);

    pixels = toGrayBinary(pixels, true, null, true);

    var canvas2 = document.createElement('canvas');

    var ctx2 = canvas2.getContext('2d');

    canvas2.width = tw;

    canvas2.height = th;

    ctx2.drawImage(image2, 0, 0, image2.width, image2.height, 0, 0, tw, th);

    var pixels2 = ctx2.getImageData(0, 0, tw, th);

    pixels2 = toGrayBinary(pixels2, true, null, true);

    var similar = 0;

    for (var i = 0, len = tw * th; i < len; i++) {

        if (pixels[i] == pixels2[i]) similar++;

    }

    similar = (similar / (tw * th)) * 100;

    return similar;

}

// 像素数据，是否二值化（bool），二值化闵值（0-255），是否返回二值化后序列（bool）

function toGrayBinary(pixels, binary, value, sn) {

    var r, g, b, g, avg = 0, len = pixels.data.length, s = '';

    for (var i = 0; i < len; i += 4) {

        avg += (.299 * pixels.data[i] + .587 * pixels.data[i + 1] + .114 * pixels.data[i + 2]);

    }

    avg /= (len / 4);

    for (var i = 0; i < len; i += 4) {

        r = .299 * pixels.data[i], g = .587 * pixels.data[i + 1], b = .114 * pixels.data[i + 2];

        if (binary) {

            if ((r + g + b) >= (value || avg)) {

                g = 255;

                if (sn) s += '1';

            } else {

                g = 0;

                if (sn) s += '0';

            }

            g = (r + g + b) > (value || avg) ? 255 : 0;

        } else {

            g = r + g + b;

        }

        pixels.data[i] = g, pixels.data[i + 1] = g, pixels.data[i + 2] = g;

    }

    if (sn) return s;

    else return pixels;

}

</script>

</head>

<body>

<div class="panel"><span>请拖拽图片一至此框内</span></div>

<div class="panel"><span>请拖拽图片二至此框内</span></div>

<div class="similar"></div>

</body>

</html>
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原文地址: https://outofmemory.cn/zaji/588934.html
Canvas识别相似图片

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