I want to use the (pica library) for image resize, but it asks me for a Uint8Array and i only have an Image object with the
src = 'data:image/jpeg;base64,/9j/4AAQ...'
I have no idea how to turn this into a Uint8Array, any thoughts?
Thanks
You will need to apply the image to a canvas and use getImageData().
Here's a simple example of how it can be done:
//create canvas, set base64 test img
var canvas = document.createElement('canvas'),
ctx = canvas.getContext('2d'),
base64 = 'data:image/jpeg;base64...'; //base64 string
//size canvas
canvas.width = 34,
canvas.height = 34;
//create image, set src to base64 and onload draw to canvas
var image = new Image();
image.onload = (function(canvas, ctx){
return function(){
ctx.drawImage(this, 0, 0);
//now we can finally get a Uint8ClampedArray
var imageData = ctx.getImageData(0, 0, 34, 34);
console.log(imageData.data);
};
})(canvas, ctx);
image.src = base64;
jsfiddle
Related
If I have an image in base64 ex.
data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAABDAAwfqNRk/rjcYX+PxrV/wtWqwJSTlboMgAAAABJRU5ErkJggg==
What's the fastest way to change a filter (ex. brightness, contrast) programmatically and without creating any img or canvas tag in the view? Then once changed, convert it back to a base64 url?
You can do this by putting the image onto a HTML canvas with filters applied, then turning that canvas back into a base64 URL.
Since you never add the canvas to the document, it will never be seen.
This is how you would do it asynchronously:
This takes about 1-10ms
function applyFiltersToImage(imageURL, callBack) {
// load the image url into an image object
const image = new Image();
image.src = imageURL;
const canvas = document.createElement("canvas");
const ctx = canvas.getContext('2d');
image.onload = () => {
canvas.width = image.width;
canvas.height = image.height;
// apply css filters here
ctx.filter = 'brightness(0.5) contrast(2)';
ctx.drawImage(image, 0, 0, canvas.width, canvas.height);
// turn canvas back into a base64 image URL
callBack(canvas.toDataURL("image/png"));
}
}
You could do it synchronously if you already have the Image instance loaded.
This is how you will do it synchronously:
function applyFiltersToImageSync(imageObject) {
const canvas = document.createElement("canvas");
const ctx = canvas.getContext('2d');
canvas.width = imageObject.width;
canvas.height = imageObject.height;
// apply css filters here
ctx.filter = 'brightness(0.5) contrast(2)';
ctx.drawImage(imageObject, 0, 0, canvas.width, canvas.height);
//turn canvas back into a base64 image
return canvas.toDataURL("image/png");
}
I have an image path which it is stored locally.
For example,
let path = 'C:\Users\Jonnie\Desktop'
How do I get the image by using JavaScript only and convert it to base64?
function imageToBase64(img)
{
var canvas, ctx, dataURL, base64;
canvas = document.createElement("canvas");
ctx = canvas.getContext("2d");
canvas.width = img.width;
canvas.height = img.height;
ctx.drawImage(img, 0, 0);
dataURL = canvas.toDataURL("image/png");
base64 = dataURL.replace(/^data:image\/png;base64,/, "");
return base64;
}
source
Now you just need to pass your image to there
You can use <canvas> for this.
Create a canvas and load in the image then use toDataURL() to get it in base64
The documentation for <canvas> can be found here
I am trying to add an image to my pdf:
var image = '../images/example.jpg';
doc.addImage(image, 'JPEG', 0, 0, 700, 145);
and I get this error:
Error: Supplied data is not a JPEG
however, when I add a base64 image:
var image = 'data:image/jpeg;base64,/9j/6GADS...'
doc.addImage(image, 'JPEG', 0, 0, 700, 145);
it works fine!
why is the first version not working?
I am trying this:
var image = $base64.encode('../images/example.jpg')
the same error above again!
what is happening here? what is the solution?
You can use this.
function toDataUrl(src, callback, outputFormat) {
// Create an Image object
var img = new Image();
// Add CORS approval to prevent a tainted canvas
img.crossOrigin = 'Anonymous';
img.onload = function() {
// Create an html canvas element
var canvas = document.createElement('CANVAS');
// Create a 2d context
var ctx = canvas.getContext('2d');
var dataURL;
// Resize the canavas to the image dimensions
canvas.height = this.height;
canvas.width = this.width;
// Draw the image to a canvas
ctx.drawImage(this, 0, 0);
// Convert the canvas to a data url
dataURL = canvas.toDataURL(outputFormat);
// Return the data url via callback
callback(dataURL);
// Mark the canvas to be ready for garbage
// collection
canvas = null;
};
// Load the image
img.src = src;
}
I have a base64 string. Is there any way I can get ctx.getImageData(); from the base64 string? If yes, please guide me.
You'd have to create a canvas, and then draw the image in the canvas to get pixel information from getImageData()
var canvas = document.createElement('canvas');
var ctx = canvas.getContext("2d");
var image = new Image();
image.onload = function() {
ctx.drawImage(image, 0, 0);
ctx.getImageData(50, 50, 100, 100);
};
image.src = "data:image/png;base64,...";
I have a base64 image string, I have created a canvas and put the base64 with the image and have given canvas height as 481 and width as 650, when I tried to display the image in html, image is coming but it is not completely filling the canvas,
Can anyone please tell me some solution to fill the image within the entire canvas, no matter what the quality of the picture.
My code is as given below
JSFiddle
var base64 = "data:image/jpeg;base64,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";
var canvas = document.createElement('canvas');
canvas.width = 650;
canvas.height = 481;
var ctx = canvas.getContext("2d");
var image = new Image();
image.onload = function () {
ctx.drawImage(image, 0, 0);
};
image.src = base64;
$('#showImage').html(canvas);
Change your onload function body to
ctx.drawImage(image, 0, 0, 650, 481);
Set the size of the canvas using natural width/height after the image has loaded:
var base64 = "data:image/jpeg;base64,/9j/4AAQSkZJ.....";
var canvas = document.createElement('canvas');
var ctx = canvas.getContext("2d");
var image = new Image();
image.onload = function () {
canvas.width = this.naturalWidth;
canvas.height = this.naturalHeight;
ctx.drawImage(this, 0, 0);
};
image.src = base64;
$('#showImage').html(canvas);