Creating artwork: How to resize images without losing clarity

Question

Creating artwork: How to resize images without losing clarity

Struggling to display an image in a canvas element that needs to be a certain percentage of its parent container's width. Despite my efforts, the image seems to blur once added to the canvas, which is not the desired effect.

I attempted to disable the blurring by setting

ctx.imageSmoothingEnabled = false

, but unfortunately, it did not solve the issue.

If anyone has suggestions on how to prevent image blurring within this canvas, I would greatly appreciate any insights!

var img = new Image();
img.src = 'https://gist.githubusercontent.com/duhaime/019f2ccb98391adbf460a10463059683/raw/c4c2bc1fa923d905aba0ef88e05c0760823d2cca/000630070000650.jpg';

img.onload = function() { 
  var canvas = document.querySelector('canvas');
  canvas.width = hidden.clientWidth;
  canvas.height = hidden.clientHeight;
  var ctx = canvas.getContext('2d');
  ctx.webkitImageSmoothingEnabled = false;
  ctx.mozImageSmoothingEnabled = false;
  ctx.imageSmoothingEnabled = false;
  ctx.drawImage(hidden,
    0, 0, this.naturalWidth, this.naturalHeight,
    0, 0, hidden.clientWidth, hidden.clientHeight)

}

#container {
  width: 800px;
  background: #efefef;
}

#hidden {
  position: absolute;
  top: -1000%;
}

#hidden,
#canvas {
  width: 60%;
}

<div id='container'>
  <img src='https://gist.githubusercontent.com/duhaime/019f2ccb98391adbf460a10463059683/raw/c4c2bc1fa923d905aba0ef88e05c0760823d2cca/000630070000650.jpg' id='hidden'>
  <canvas></canvas>
</div>

javascript html css canvas

Answer 1

Answer №1

Understanding the Difference Between Canvas Resolution and Display Size

Upon examining the image, it appears to be 444px by 800px in size, indicating a low resolution. The actual display of the image will vary depending on the device used.

In your query, you have specified the canvas display width as 60% of the container's size, while setting the canvas resolution to 444px by 800px.

It is probable that the display width and the canvas resolution do not align.

Distinguishing Canvas Display Size and Resolution

canvas.style.width and canvas.style.height define the area on the page that the image occupies and are unrelated to the canvas resolution.

Understanding Canvas Resolution

The properties canvas.width and canvas.height indicate the pixel resolution of the canvas, representing the actual number of pixels used to store the image data.

Dealing with Browser-Induced Blur

If the canvas is stretched over a larger area than its resolution, browsers may introduce blurring effects due to the scaling discrepancy.

To prevent this blur, apply the CSS attribute image-rendering: pixelated; as shown in the example below.

// JavaScript code for handling image rendering
var img = new Image();
img.src = 'https://gist.githubusercontent.com/duhaime/019f2ccb98391adbf460a10463059683/raw/c4c2bc1fa923d905aba0ef88e05c0760823d2cca/000630070000650.jpg';

img.onload = function() { 
  canvas.width = this.naturalWidth;
  canvas.height = this.naturalHeight;
  var ctx = canvas.getContext('2d');
  ctx.drawImage(this, 0, 0);
}

.big {
  width:100%;
  image-rendering: pixelated;
}

<canvas class="big" id="canvas"></canvas>

Enhancing Two-Tone Black & White Images

For low-resolution two-tone images, improving quality can be challenging. However, you can increase contrast to reduce blurriness caused during rendering.

Utilize screen and color-burn composite operations to enhance the left half of the image with better contrast while maintaining a less pixelated appearance.

// JavaScript code for enhancing contrast in B/W images
var img = new Image();
img.src = 'https://gist.githubusercontent.com/duhaime/019f2ccb98391adbf460a10463059683/raw/c4c2bc1fa923d905aba0ef88e05c0760823d2cca/000630070000650.jpg';

img.onload = function() { 
  const bounds = canvas.getBoundingClientRect(); //Get the canvas display sise
  
  canvas.width = bounds.width;
  canvas.height = this.naturalHeight * (bounds.width / this.naturalWidth);
  var ctx = canvas.getContext('2d');
  // Draw the image to canvas 
  ctx.drawImage(this, 0, 0, canvas.width, canvas.height);
  // Apply composite operations to improve contrast
  // Additional processing steps omitted here for brevity
}

.big {
  width:100%;
}

<canvas class="big" id="canvas"></canvas>

Answer 2

Understanding the Difference Between Canvas Resolution and Display Size

Upon examining the image, it appears to be 444px by 800px in size, indicating a low resolution. The actual display of the image will vary depending on the device used.

In your query, you have specified the canvas display width as 60% of the container's size, while setting the canvas resolution to 444px by 800px.

It is probable that the display width and the canvas resolution do not align.

Distinguishing Canvas Display Size and Resolution

canvas.style.width and canvas.style.height define the area on the page that the image occupies and are unrelated to the canvas resolution.

Understanding Canvas Resolution

The properties canvas.width and canvas.height indicate the pixel resolution of the canvas, representing the actual number of pixels used to store the image data.

Dealing with Browser-Induced Blur

If the canvas is stretched over a larger area than its resolution, browsers may introduce blurring effects due to the scaling discrepancy.

To prevent this blur, apply the CSS attribute image-rendering: pixelated; as shown in the example below.

// JavaScript code for handling image rendering
var img = new Image();
img.src = 'https://gist.githubusercontent.com/duhaime/019f2ccb98391adbf460a10463059683/raw/c4c2bc1fa923d905aba0ef88e05c0760823d2cca/000630070000650.jpg';

img.onload = function() { 
  canvas.width = this.naturalWidth;
  canvas.height = this.naturalHeight;
  var ctx = canvas.getContext('2d');
  ctx.drawImage(this, 0, 0);
}

.big {
  width:100%;
  image-rendering: pixelated;
}

<canvas class="big" id="canvas"></canvas>

Enhancing Two-Tone Black & White Images

For low-resolution two-tone images, improving quality can be challenging. However, you can increase contrast to reduce blurriness caused during rendering.

Utilize screen and color-burn composite operations to enhance the left half of the image with better contrast while maintaining a less pixelated appearance.

// JavaScript code for enhancing contrast in B/W images
var img = new Image();
img.src = 'https://gist.githubusercontent.com/duhaime/019f2ccb98391adbf460a10463059683/raw/c4c2bc1fa923d905aba0ef88e05c0760823d2cca/000630070000650.jpg';

img.onload = function() { 
  const bounds = canvas.getBoundingClientRect(); //Get the canvas display sise
  
  canvas.width = bounds.width;
  canvas.height = this.naturalHeight * (bounds.width / this.naturalWidth);
  var ctx = canvas.getContext('2d');
  // Draw the image to canvas 
  ctx.drawImage(this, 0, 0, canvas.width, canvas.height);
  // Apply composite operations to improve contrast
  // Additional processing steps omitted here for brevity
}

.big {
  width:100%;
}

<canvas class="big" id="canvas"></canvas>

Answer 3

Answer №2

It's hard to say if this is exactly what you're looking for, but I was taken aback by the top: -1000% value. In this scenario, when the container has a "position: relative" property, the percentage-based properties of its children will be relative to the parent element.

let image = new Image();
image.src = 'https://example.com/image.jpg';

image.onload = function() { 
  let canvas = document.querySelector('canvas');
  canvas.width = hidden.clientWidth;
  canvas.height = hidden.clientHeight;
  let ctx = canvas.getContext('2d');
  ctx.webkitImageSmoothingEnabled = false;
  ctx.mozImageSmoothingEnabled = false;
  ctx.imageSmoothingEnabled = false;
  ctx.drawImage(hidden,
    0, 0, this.naturalWidth, this.naturalHeight,
    0, 0, hidden.clientWidth, hidden.clientHeight)

}

 

#container {
  width: 800px;
  background: #efefef;
  position:relative;
}

#hidden {
  position: absolute;
  top: 0;
  right: 0;
}
#hidden, canvas {
  width: 50%;
}

<div id='container'>
  <img src='https://example.com/image.jpg' id='hidden'>
  <canvas></canvas>
</div>

Answer 4

It's hard to say if this is exactly what you're looking for, but I was taken aback by the top: -1000% value. In this scenario, when the container has a "position: relative" property, the percentage-based properties of its children will be relative to the parent element.

let image = new Image();
image.src = 'https://example.com/image.jpg';

image.onload = function() { 
  let canvas = document.querySelector('canvas');
  canvas.width = hidden.clientWidth;
  canvas.height = hidden.clientHeight;
  let ctx = canvas.getContext('2d');
  ctx.webkitImageSmoothingEnabled = false;
  ctx.mozImageSmoothingEnabled = false;
  ctx.imageSmoothingEnabled = false;
  ctx.drawImage(hidden,
    0, 0, this.naturalWidth, this.naturalHeight,
    0, 0, hidden.clientWidth, hidden.clientHeight)

}

 

#container {
  width: 800px;
  background: #efefef;
  position:relative;
}

#hidden {
  position: absolute;
  top: 0;
  right: 0;
}
#hidden, canvas {
  width: 50%;
}

<div id='container'>
  <img src='https://example.com/image.jpg' id='hidden'>
  <canvas></canvas>
</div>

Creating artwork: How to resize images without losing clarity

Answer №1

Understanding the Difference Between Canvas Resolution and Display Size

Distinguishing Canvas Display Size and Resolution

Understanding Canvas Resolution

Dealing with Browser-Induced Blur

Enhancing Two-Tone Black & White Images

Answer №2

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