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JavaScript: Multiple cropping selection in one image?

PS: Is it not a research kind of question! I have been trying to do this from very long time.
I am trying to make web based an image editor where user can select multiple cropping area and after selection save/download all the image area. like below.
As of now I discovered two libraries
1.Cropper.JS where is only single selection feature is available.
2.Jcrop where only single selection area restrictions.
I am currently using cropper.Js but it seems impossible for me to make multiple selection cropping.
Any help is much appreciated.if any other method/library available in JavaScript, Angular or PHP or reactJS for multiple image area selection and crop and download in one go as in the image below.
As per #Keyhan Answer I am Updating my Jcrop library Code
<div style="padding:0 5%;">
<img id="target" src="https://d3o1694hluedf9.cloudfront.net/market-750.jpg">
</div>
<button id="save">Crop it!</button>
<link rel="stylesheet" href="https://unpkg.com/jcrop/dist/jcrop.css">
<script src="https://unpkg.com/jcrop"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
JavaScript
<script>
setImage();
var jcp;
var jcp;
Jcrop.load('target').then(img => {
//You can enable multiple cropping with this line:
jcp = Jcrop.attach(img, { multi: true });
});
// to fix security issue when trying to convert to Data URI
function setImage() {
document.getElementById('target').setAttribute('crossOrigin', 'anonymous');
document.getElementById('target').src = 'https://d3o1694hluedf9.cloudfront.net/market-750.jpg';
}
var link = document.getElementById('save');
link.onclick = function () {
//we check if at least one crop is available
if (jcp.active) {
var i = 0;
var fullImg = document.getElementById("target");
//we are looping cropped areas
for (area of jcp.crops) {
i++;
//creating temp canvas and drawing cropped area on it
canvas = document.createElement("canvas");
canvas.setAttribute('width', area.pos.w);
canvas.setAttribute('height', area.pos.h);
ctx = canvas.getContext("2d");
ctx.drawImage(fullImg, area.pos.x, area.pos.y, area.pos.w, area.pos.h, 0, 0, area.pos.w, area.pos.h);
//creating temp link for saving/serving new image
temp = document.createElement('a');
temp.setAttribute('download', 'area' + i + '.jpg');
temp.setAttribute('href', canvas.toDataURL("image/jpg").replace("image/jpg", "image/octet-stream"));
temp.click();
}
}
};
</script>

I tried to explain the code with comments:
var jcp;
Jcrop.load('target').then(img => {
//You can enable multiple cropping with this line:
jcp = Jcrop.attach(img,{multi:true});
});
//assuming you have a button with id="save" for exporting cropped areas
var link=document.getElementById('save');
link.onclick = function(){
//we check if at least one crop is available
if(jcp.active){
var i=0;
var fullImg = document.getElementById("target");
//we are looping cropped areas
for(area of jcp.crops){
i++;
//creating temp canvas and drawing cropped area on it
canvas = document.createElement("canvas");
canvas.setAttribute('width',area.pos.w);
canvas.setAttribute('height',area.pos.h);
ctx = canvas.getContext("2d");
ctx.drawImage(fullImg, area.pos.x, area.pos.y, area.pos.w, area.pos.h, 0, 0, area.pos.w, area.pos.h);
//creating temp link for saving/serving new image
temp = document.createElement('a');
temp.setAttribute('download', 'area'+i+'.jpg');
temp.setAttribute('href', canvas.toDataURL("image/jpg").replace("image/jpg", "image/octet-stream"));
temp.click();
}
}
};
EDIT: As you commented it would be nicer if we have local image loader, we can add a file input to our html
<img id="target" />
<br/>
<input type="file" id="imageLoader" name="imageLoader"/><!-- add this for file picker -->
<button id="save">save</button>
and a function to our js to handle it
var jcp;
var save=document.getElementById('save');
var imageLoader = document.getElementById('imageLoader');
var img = document.getElementById("target");
imageLoader.onchange=function handleImage(e){//handling our image picker <input>:
var reader = new FileReader();
reader.onload = function(event){
img.src = event.target.result;
}
reader.readAsDataURL(e.target.files[0]);
}
save.onclick = function(){
if(jcp&&jcp.active){
var i=0;
for(area of jcp.crops){
i++;
canvas = document.createElement("canvas");
canvas.setAttribute('width',area.pos.w);
canvas.setAttribute('height',area.pos.h);
ctx = canvas.getContext("2d");
ctx.drawImage(img, area.pos.x, area.pos.y, area.pos.w, area.pos.h, 0, 0, area.pos.w, area.pos.h);
temp = document.createElement('a');
temp.setAttribute('download', 'area'+i+'.jpg');
temp.setAttribute('href', canvas.toDataURL("image/jpg").replace("image/jpg", "image/octet-stream"));
temp.click();
}
}
};
Jcrop.load('target').then(img => {
jcp = Jcrop.attach(img,{multi:true});
});

Yes, #keyhan was right <input type="file"> is another question, but still, I am giving you an idea of how to implement Kayhan's code above.
<div>
<input type="file" id="image-input" accept="image/*">
<!-- img id name should be "target" as it is also using by Jcrop -->
<img id="target"></img>
</div>
and Now you can put below JavaScript Code just above setImage()
<script>
let imgInput = document.getElementById('image-input');
imgInput.addEventListener('change', function (e) {
if (e.target.files) {
let imageFile = e.target.files[0];
var reader = new FileReader();
reader.onload = function (e) {
var img = document.createElement("img");
img.onload = function (event) {
var MAX_WIDTH = 1600;
var MAX_HEIGHT = 800;
var width = img.width;
var height = img.height;
// Change the resizing logic
if (width > height) {
if (width > MAX_WIDTH) {
height = height * (MAX_WIDTH / width);
width = MAX_WIDTH;
}
} else {
if (height > MAX_HEIGHT) {
width = width * (MAX_HEIGHT / height);
height = MAX_HEIGHT;
}
}
// Dynamically create a canvas element
var canvas = document.createElement("canvas");
canvas.width = width;
canvas.height = height;
// var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
// Actual resizing
ctx.drawImage(img, 0, 0, width, height);
// Show resized image in preview element
var dataurl = canvas.toDataURL(imageFile.type);
document.getElementById("target").src = dataurl;
}
img.src = e.target.result;
}
reader.readAsDataURL(imageFile);
}
});
</script>

Slick slider error: TypeError: o[i].slick is undefined

I'm trying to make it so that when the search button is pressed it will clear the previous search results from the screen and create the new search results. However when I do this, I get a slick slider error and all my items line up vertically. I'm not exactly sure if the thing I'm trying to do is possible to do with slick slider because I am essentially creating the search-slider div. When I don't remove() my search-sliderdiv, the previous results will be loaded next to the old results but they will be rendered by slick slider. I'm not sure where I should go from here.
FYI, the snippet will not run on here. I made it for ease of looking at the code.
If anyone could help, it would be greatly appreciated. Thanks.
$(function() {
$('#search').click(function() {
var nameVal = $('#shouhinName').val();
var makerVal = $('#makerName').val();
var categoryVal = $('#selectText').val();
var sliderVal = $('#hideme').val();
$.ajax({
type: "POST",
url: "shelf/test",
data: {
shouhinName: nameVal,
makerName: makerVal,
selectText: categoryVal,
best: sliderVal
},
success: function hi(j_data) {
alert(j_data.url);
// create a new div element
//const images = j_data;
// console.log(imagePath);
/* for (const image of imagePath) {
const img = document.createElement("img");
if (image.slice(0, 5) == "shelf") {
img.src = `/check/assets/img/${image}`;
} else {
img.src = '/check/assets/img/noimage.png';
}
img.classList.add("new");
var div = document.createElement("div");
div.id = `${image}`
div.classList.add("image");
linebreak = document.createElement("br");
// div.classList.add("column");
document.getElementById('search-slider').appendChild(div);
// document.getElementById('rows').appendChild(div);
//img.setAttribute("style", "text-align: center;");
// document.body.appendChild(img);
document.getElementById(image).appendChild(img);
} */
console.log(j_data);
// console.log(images);
let index = 0;
const display = "table"; // or "grid" if horizontal, but this migh depend where you place the rest of the code, cause i added the style to the body
const x = 0;
const y = 0;
document.body.style.display = display;
$('#search-slider').remove();
// function createHTML() {
// console.log("E: Execute & R: Request & I: Informative");
//loop to go true all images
const search = document.createElement("div");
search.id = 'search-slider';
search.className = "search-items";
console.log(search.id);
document.getElementById("divbox").appendChild(search);
for (const image of j_data.url) {
// console.log();
//each image will correspond to a canvas element
const canvas = document.createElement("canvas");
const ctx = canvas.getContext("2d");
//each canvas element will has is own properties (in this case all the same)
canvas.id = "option" + [index];
var canId = canvas.id;
var tooltip = j_data.tooltip;
// console.log(tooltip[index]);
// tooltip is the array
// var tooltipSel = document.getElementById(canId);
/* canvas.height = images.height;
canvas.width = images.width; */
// canvas.setAttribute('heigth', '0');
canvas.setAttribute('width', '75px');
canvas.setAttribute('padding-top', '56.25%');
canvas.setAttribute('object-fit', 'contain');
canvas.setAttribute('data-html', 'true');
// canvas.title = "hi";
// console.log('#'+ canvas.id);
var div = document.createElement("div");
div.setAttribute('data-html', 'true');
div.id = j_data.itemid[index]; //image.slice(26, 34);
// $('#'+div.id).remove();
/* var itemID = div.id;
var itemidArray = [];
itemidArray = itemID; */
// console.log(itemidArray);
console.log(div.id);
// canvas.style.padding = "10px";
// canvas.classList.add("suiteiCanvas");
//function to get the corresponded image of that particular canvas element
drawImages(canvas);
//add an event listener for when a user click on the particular canvas
canvas.addEventListener("click", optionClicke, false);
//all html part was handle we can append it to the body
// document.body.appendChild(canvas);
//console.log(image);
var text = j_data.tooltip[index];
/* div.title = "";
$('#' + div.id).data('powertip', function() {
return div.title = tooltip[index];
}); */
div.title = text;
document.getElementById('search-slider').appendChild(div);
document.getElementById(div.id).appendChild(canvas);
// $(div.id).prepend(text);
index++;
}
// }
// console.log(itemidArray);
function drawImages(canvas) {
//we need to use the getContext canvas function to draw anything inside the canvas element
const ctx = canvas.getContext("2d");
const background = new Image();
// for text
//This is needed because if the drawImage is called from a different place that the createHTML function
//index value will not be at 0 and it will for sure with an heigher id that the one expected
//so we are using regex to remove all letters from the canvas.id and get the number to use it later
index = canvas.id.replace(/\D/g, "");
//console.log('E: Drawing image ' + index + ' on canvas ' + canvas.id);
//get the image url using the index to get the corresponded image
// background.src = images.url[index];
if (j_data.url[index] !== '/check/assets/img/noimage.png') {
background.src = "/check/assets/img/" + j_data.url[index];
} else {
background.src = '/check/assets/img/noimage.png'
}
//no idea why but to place the image, we need to use the onload event
//https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/drawImage
background.onload = function() {
ctx.drawImage(background, 0, 0, canvas.width, canvas.height);
};
/* background.onerror = function() {
const text = "インバ ど";
ctx.fillText(text, 0, 0 + 10 * 1);
}; */
}
function drawX(canvas, item) {
const ctx = canvas.getContext("2d");
// console.log("E: Placing X on canvas " + canvas.id);
ctx.beginPath();
ctx.arc(40, 75, 25, 0, 2 * Math.PI, false);
ctx.lineWidth = 5;
ctx.strokeStyle = "#FF0000";
ctx.closePath();
ctx.stroke();
console.log(item);
hdnName.value = item;
}
/* function fillTextLine(canvas, x, y) {
var text = "インバ ど";
const ctx = canvas.getContext("2d");
var textList = text.split("　");
var lineHeight = ctx.measureText("あ").width;
textList.forEach(function(text, i) {
ctx.fillText(text, x, y + lineHeight * i);
});
} */
function clear(canvas) {
// console.log("E: clearing canvas " + canvas.id);
canvas.getContext("2d").clearRect(0, 0, canvas.width, canvas.height);
drawImages(canvas);
}
function optionClicke(e) {
log = true;
const canvas = document.getElementsByTagName("canvas");
var hdnName = document.getElementById("sendServ");
let index = 0;
for (const option of canvas) {
if (log)
// console.log("I: User clicked at option " + e.target.id + ":" + option.id);
log = false;
if (e.target.id === option.id) {
// console.log("R: Drawing request at canvas " + option.id);
// console.log(j_data.itemid[index]);
const item = j_data.itemid[index];
console.log('draw' + item);
console.log(index);
drawX(option, item);
} else {
// console.log("R: Clearing request at canvas " + option.id);
clear(option);
//console.log('clear'+item);
}
index++;
}
}
$('.search-items').slick('unslick').slick('reinit');
$(document).ready(function() {
$('.search-items').not('.slick-initialized').slick({
infinite: false, //true
slidesToShow: 8,
slidesToScroll: 8,
arrows: true,
centerMode: false,
width: 200,
prevArrow: $('.prev'),
nextArrow: $('.next')
});
});
// console.log(j_data);
// need to do my image processing in here
},
error: function(xhr, status, error) {
console.log("post error");
console.log(error);
alert(error);
},
complete: function(xhr, status) {
console.log("fin");
},
});
});
});
.search-items{
max-width: 1800px;
}
<div class="search-items" id="search-slider">
</div>

I removed
let index = 0;
const display = "table"; // or "grid" if horizontal, but this migh depend where you place the rest of the code, cause i added the style to the body
const x = 0;
const y = 0;
document.body.style.display = display;
$('#search-slider').remove();
// function createHTML() {
// console.log("E: Execute & R: Request & I: Informative");
//loop to go true all images
const search = document.createElement("div");
search.id = 'search-slider';
search.className = "search-items";
console.log(search.id);
document.getElementById("divbox").appendChild(search);
and reverted my code by to where the items were lining up to each other.
I needed to add $('.search-items').slick('slickRemove', 0);
So I made a for loop to count my item id's before my loop that went over my images.
for (const id of j_data.itemid) {
$('.search-items').slick('slickRemove', 0);
}
This removed the first search result every time I pressed my search button.
Hopefully this helps someone else.

How do I get the full canvas content (even the hidden ones) with Javascript?

I am currently working on a Javascript project and I am struggling with exporting the entire SVG image on the canvas. So far I've been only able to export the visible part of the canvas, with out the "hidden" parts.
How do I capture the full canvas content?
Is there a way to do it without messing around with the original canvas size?
I am using D3.js V3
Screenshot of my project
Here's my code:
var svgString;
window.onload = function(){
setTimeout(function() {
exportSVG = document.getElementById("canvas");
document.getElementById("canvas").style.fontFamily= "lato";
document.getElementById("canvas").style.width= exportSVG.getBBox().width * 1;
document.getElementById("canvas").style.height= exportSVG.getBBox().height * 1;
svgString = getSVGString(exportSVG);
console.log(exportSVG.getBBox().width + " / " + exportSVG.getBBox().height);
svgString2Image(svgString, exportSVG.getBBox().width, exportSVG.getBBox().height, 'png', save); // passes Blob and filesize String to the callback
console.log("svg export code loaded");
// console.log(svgString.getBBox().width); document.getElementById("canvas").getBBox().width
}, 5000);
};
function save(dataBlob, filesize) {
saveAs(dataBlob, 'D3 vis exported to PNG.png'); // FileSaver.js function
}
// Below are the functions that handle actual exporting:
// getSVGString ( svgNode ) and svgString2Image( svgString, width, height, format, callback )
function getSVGString(svgNode) {
svgNode.setAttribute('xlink', 'http://www.w3.org/1999/xlink');
var cssStyleText = getCSSStyles(svgNode);
appendCSS(cssStyleText, svgNode);
var serializer = new XMLSerializer();
var svgString = serializer.serializeToString(svgNode);
svgString = svgString.replace(/(\w+)?:?xlink=/g, 'xmlns:xlink='); // Fix root xlink without namespace
svgString = svgString.replace(/NS\d+:href/g, 'xlink:href'); // Safari NS namespace fix
return svgString;
function getCSSStyles(parentElement) {
var selectorTextArr = [];
// Add Parent element Id and Classes to the list
selectorTextArr.push('#' + parentElement.id);
for (var c = 0; c < parentElement.classList.length; c++)
if (!contains('.' + parentElement.classList[c], selectorTextArr))
selectorTextArr.push('.' + parentElement.classList[c]);
// Add Children element Ids and Classes to the list
var nodes = parentElement.getElementsByTagName("*");
for (var i = 0; i < nodes.length; i++) {
var id = nodes[i].id;
if (!contains('#' + id, selectorTextArr))
selectorTextArr.push('#' + id);
var classes = nodes[i].classList;
for (var c = 0; c < classes.length; c++)
if (!contains('.' + classes[c], selectorTextArr))
selectorTextArr.push('.' + classes[c]);
}
// Extract CSS Rules
var extractedCSSText = "";
for (var i = 0; i < document.styleSheets.length; i++) {
var s = document.styleSheets[i];
try {
if (!s.cssRules) continue;
} catch (e) {
if (e.name !== 'SecurityError') throw e; // for Firefox
continue;
}
var cssRules = s.cssRules;
for (var r = 0; r < cssRules.length; r++) {
if (contains(cssRules[r].selectorText, selectorTextArr))
extractedCSSText += cssRules[r].cssText;
}
}
return extractedCSSText;
function contains(str, arr) {
return arr.indexOf(str) === -1 ? false : true;
}
}
function appendCSS(cssText, element) {
var styleElement = document.createElement("style");
styleElement.setAttribute("type", "text/css");
styleElement.innerHTML = cssText;
var refNode = element.hasChildNodes() ? element.children[0] : null;
element.insertBefore(styleElement, refNode);
}
}
function svgString2Image(svgString, width, height, format, callback) {
var format = format ? format : 'png';
var imgsrc = 'data:image/svg+xml;base64,' + btoa(unescape(encodeURIComponent(svgString))); // Convert SVG string to data URL
var canvas = document.createElement("canvas");
var context = canvas.getContext("2d");
canvas.width = width;
canvas.height = height;
var image = new Image();
image.onload = function() {
context.clearRect(0, 0, width, height);
context.drawImage(image, 0, 0, width, height);
canvas.toBlob(function(blob) {
var filesize = Math.round(blob.length / 1024) + ' KB';
if (callback) callback(blob, filesize);
});
};
image.src = imgsrc;
}

Simply change your <svg> viewBox attribute before you serialize it to a string so that it displays everything:
var svg = document.querySelector('svg');
var toExport = svg.cloneNode(true); // avoids having to reset everything afterward
// grab its inner content BoundingBox
var bb = svg.getBBox();
// update its viewBox so it displays all its inner content
toExport.setAttribute('viewBox', bb.x + ' ' + bb.y + ' ' + bb.width + ' ' + bb.height);
toExport.setAttribute('width', bb.width);
toExport.setAttribute('height', bb.height);
var svgAsStr = new XMLSerializer().serializeToString(toExport);
var blob = new Blob([svgAsStr], {type: 'image/svg+xml'});
var img = new Image();
img.onload = drawToCanvas;
img.src = URL.createObjectURL(blob);
function drawToCanvas(evt) {
var canvas = document.createElement('canvas');
canvas.width = this.width;
canvas.height = this.height;
canvas.getContext('2d').drawImage(this, 0,0);
document.body.appendChild(canvas);
}
svg{border: 1px solid blue}
canvas{border: 1px solid green}
<svg width="50" height="50" viewBox="0 0 50 50">
<rect x="0" y="0" width="200" height="50" fill="#CCC"/>
</svg>

Import long html into split PDF

My scenario is:
On clicking a button, import datas on a html into a PDF file.
Since this PDF must have some complicated required style, so my first step is to transfer this page into a image using html2canvas.js and then import this image to a PDF with jsPDF.js
And when the data is too large the PDF must be split to hold all the data,to do this,so I used the codes here: https://github.com/MrRio/jsPDF/pull/397
My problem is: on firefox the splited page on PDF on page 2 or 3...cannot be shown, they are totally blank. but on page 1 it is fine. (this is for firefox)
I tested other browsers they are all fine. pls someone could throw some light on how to fix this?
Here is my plnkr:
http://plnkr.co/edit/ElvAsriK2nssq2U9pgKX?p=preview
function initTemplate(){
datas=getData();
var templateData=_.template($('#tpl').html(), datas);
$('#tplW').html(templateData);
getPDF();
// $('#tplW').append(_.template($('#tpl').html(), datas));
// $('body').html( _.template($('#tpl').html(), datas));
}
function getData(){
var htmlData=$(".MsoNormalTable .inner").find("tr.tablerow");
var datas=[];
$.each(htmlData,function(i,v){
var d=[];
var tds=$(v).find("td");
$.each(tds,function(index,val){
d.push($(val).text());
});
datas.push(d);
});
return datas;
}
function getPDF() {
// initTemplate();
html2canvas($('#tplW')[0], {
onrendered: function(canvas){
canvasToImageSuccess(canvas);
}
});
function canvasToImage (canvas){
var img = new Image();
var dataURL = canvas.toDataURL('image/png');
img.src = dataURL;
return img;
};
function canvasShiftImage (oldCanvas,shiftAmt){
shiftAmt = parseInt(shiftAmt) || 0;
if(!shiftAmt){ return oldCanvas; }
var newCanvas = document.createElement('canvas');
newCanvas.height = oldCanvas.height - shiftAmt;
newCanvas.width = oldCanvas.width;
var ctx = newCanvas.getContext('2d');
var img = canvasToImage(oldCanvas);
ctx.drawImage(img,0, shiftAmt, img.width, img.height, 0, 0, img.width, img.height);
return newCanvas;
};
function canvasToImageSuccess (canvas){
var pdf = new jsPDF('l','px'),
pdfInternals = pdf.internal,
pdfPageSize = pdfInternals.pageSize,
pdfScaleFactor = pdfInternals.scaleFactor,
pdfPageWidth = pdfPageSize.width,
pdfPageHeight = pdfPageSize.height,
totalPdfHeight = 0,
htmlPageHeight = canvas.height,
htmlScaleFactor = canvas.width / (pdfPageWidth * pdfScaleFactor),
safetyNet = 0;
while(totalPdfHeight < htmlPageHeight && safetyNet < 15){
var newCanvas = canvasShiftImage(canvas, totalPdfHeight);
pdf.addImage(newCanvas, 'png', 0, 0, pdfPageWidth, 0, null, 'NONE');
totalPdfHeight += (pdfPageHeight * pdfScaleFactor * htmlScaleFactor);
if(totalPdfHeight < htmlPageHeight){
pdf.addPage();
}
safetyNet++;
}
pdf.save('test.pdf');
};
}

You should use canvas-to-blob and FileSaver.js
and modify this line:
pdf.save('test.pdf');
to this:
var data = pdf.output();
var buffer = new ArrayBuffer(data.length);
var array = new Uint8Array(buffer);
for (var i = 0; i < data.length; i++) {
array[i] = data.charCodeAt(i);
}
var blob = new Blob(
[array],
{type: 'application/pdf', encoding: 'raw'}
);
saveAs(blob, "test.pdf");
You can check it out here.
It worked for me on Mac, Firefox.
I found this solution here.

Images not loading on website

The problem I have is that when the page is loaded sometimes it displays all the images, sometimes just 2 images and sometimes all. I don´t know why this is happening.
Any ideas?
$('#banners .box img').each(function(index){
var randval = (index+1)*100;
var _this = $(this)
setTimeout(function(){
_this.attr('id' , 'banner' + index);
to_canvas('banner' + index, 300, 223);
}, randval)
});
to_canvas function:
function to_canvas(im,w,h){
var canvas;
var imageBottom;
var im_w = w;
var im_h = h;
var imgData;
var pix;
var pixcount = 0;
var paintrow = 0;
var multiplyColor = [70, 116, 145];
var x_offset = Math.floor(($('#'+im).attr('width') - im_w)/2);
var y_offset = Math.floor(($('#'+im).attr('height') - im_h)/2);
imageBottom = document.getElementById(im);
canvas = document.createElement('canvas');
canvas.width = im_w;
canvas.height = im_h;
imageBottom.parentNode.insertBefore(canvas, imageBottom);
ctx = canvas.getContext('2d');
ctx.drawImage(imageBottom, -x_offset , -y_offset);
imgData = ctx.getImageData(0, 0, canvas.width, canvas.height);
pix = imgData.data;
for (var i = 0 ; i < pix.length; i += 4) {
if(pixcount > im_w - (im_h - paintrow) ){
pix[i ] = multiply(multiplyColor[0], pix[i ]);
pix[i+1] = multiply(multiplyColor[1], pix[i+1]);
pix[i+2] = multiply(multiplyColor[2], pix[i+2]);
}
if(pixcount < im_w-1){
pixcount++;
}else{
paintrow++;
pixcount = 0;
}
}
ctx.putImageData(imgData, 0, 0);
$('#'+im).remove();
}
function multiply(topValue, bottomValue){
return topValue * bottomValue / 255;
}
I'm using the canvas function to add a triangle with multiply effect (like Photoshop).

Make sure the images are loaded :
$('#banners .box img').each(function(index, elem){
var randval = (index+1)*100,
self = this,
img = new Image(); // create image object
img.onload = function() { // wait until it's loaded
setTimeout(function(){
self.id = 'banner' + index;
to_canvas('banner' + index, 300, 223);
}, randval)
}
img.src = elem.src; // set source to same as elem
});

Wrap it all in this code to make sure the images are loaded before you execute your script. When you initially load your page, it caches the images(stores them in temp memory), but not before all your elements are rendered. When you reload, it reads the images from the cache–which is much faster than refetching the images again from the server–and therefore the images load about the same time everything else does. This results in visible images.
Like I said, to get your page to work, make sure everything is loaded, then run your script.
$(window).load(function(){
...your scripts(you can exclude functions definitions from this scope)
}