Image Upscaling: A Detailed Guide for Beginners

If you're creating posters using Midjourney or other AI image generators, you may need to upscale your artwork before printing it.

But what exactly is upscaling, and how do you know if your image is good enough for printing?

⓵ What is upscaling?

An AI-generated image might look fantastic on your screen, but it may not contain enough pixels to look sharp when printed as a large poster.

Upscaling increases the number of pixels in an image, making it more suitable for printing at larger sizes.

There are two ways of doing this:

Normal resizing: Enlarges an image by estimating additional pixels from the existing ones. This doesn't add meaningful new detail and can leave the image looking blurry.
AI upscaling: Uses AI to estimate and recreate details, often producing cleaner edges and a sharper-looking image.

AI upscaling can improve an image, but it isn't guaranteed to produce perfect results.

⓶ Forget about DPI. Focus on pixels.

When preparing artwork for printing, you'll often hear that your image needs to be 300 DPI. But what does that actually mean, and is it really what you should be focusing on?

First, let's understand three terms you'll come across:

Pixels: The tiny squares that make up a digital image. The dimensions of your image, such as 4000 × 6000 pixels, tell you how many pixels it contains.
PPI (Pixels Per Inch): The number of image pixels used per inch when printing.
DPI (Dots Per Inch): Technically refers to the tiny ink dots a printer produces. However, people often use DPI when they actually mean PPI.

But here's the important part: Simply changing an image from 72 to 300 DPI or PPI, without resampling it, doesn't add more pixels or improve its quality. What matters is having enough pixels for the size you want to print, along with good-quality artwork.

⓷ How many pixels do I need?

The larger your poster, the more pixels you'll generally need to maintain a sharp image.

Here's a handy reference showing suggested pixel dimensions for high-quality printing across common poster sizes:

5x7" - 1500 × 2100

6x8" - 1800 × 2400

8x10" - 2400 × 3000

A4 - 2500 × 3500

11x14" - 3300 × 4200

11x17" - 3300 × 5100

A3 - 3500 × 5000

12x16" - 3600 × 4800

12x18" - 3600 × 5400

16x20" - 4800 × 6000

16x24" - 4800 × 7200

A2 - 5000 × 7000

18x24" - 5400 × 7200

20x28" - 6000 × 8400

A1 - 7000 × 9900

24x32" - 7200 × 9600

24x36" - 7200 × 10800

28x40" - 8400 × 12000

30x40" - 9000 × 12000

A0 - 9900 × 14000

Important: These are useful targets, not strict minimum requirements. Larger posters are often viewed from further away and can still look good with fewer pixels.

Also, having enough pixels doesn't automatically guarantee a good print. The quality of the original artwork matters too.

⓸ How much should I upscale?

That depends on the dimensions of your original image and the size you want to print.

Let's use the shrimp artwork from the examples below.

Our original image measures 1054 × 1492 pixels, here's what happens when we upscale it:

Original - 1054 x 1492 pixels
2x upscale - 2108 x 2984 pixels
4x upscale - 4216 x 5968 pixels
6x upscale - 6324 x 8952 pixels

For example, if we wanted to create an A2 poster, our recommended target would be approximately 5000 × 7000 pixels.

In this example, a 4x upscale would fall below our A2 target, while a 6x upscale would exceed it before any cropping.

Remember that different poster proportions may require some cropping, even when your image has enough pixels.

Does that mean you should always upscale by 6x? Not at all! Choose the amount of upscaling based on your original image dimensions and intended print size. Upscaling more than necessary can create unnecessarily large files and sometimes introduce unwanted details.

⓹ Three practical examples

Let's look at three practical examples using the same AI-generated image to see how upscaling affects the final result.

Ⓐ Scenario A: Using AI-generated artwork without further editing

In this example, we compare the original AI-generated image (1054 × 1492 pixels) with its upscaled version (6324 × 8952 pixels).

Both are displayed at approximately the same size, using different zoom levels for a fair comparison.

On the left: The original looks blurry and pixelated when enlarged, particularly around the eyebrow and eye.

On the right: The AI-upscaled version has smoother curves, sharper edges and better-defined details.

The takeaway: If your AI-generated artwork is already your finished poster, upscale it if needed, check the quality and make sure its dimensions are suitable for the print size you want to offer.

Ⓑ Scenario B: Upscaling your artwork before importing it into Canva

For this comparison, we created two A0 posters in Canva, both exported at exactly the same dimensions: 9933 × 14043 pixels.

On the left: The original low-resolution artwork was stretched to fill the A0 canvas, leaving the edges looking soft and blurry.

On the right: The artwork was AI-upscaled before being imported into Canva. The result has noticeably cleaner edges and better-defined details.

The takeaway: Exporting a poster at the recommended pixel dimensions doesn't guarantee a sharp image. It's generally better to upscale the original artwork before importing it into Canva.

This time, we created an A2 poster using the original low-resolution image, exported it from Canva and then AI-upscaled the finished poster.

On the left: The original artwork was stretched to fit the A2 canvas and exported at 4961 × 7016 pixels. The details appear soft and blurry.

On the right: The finished poster was AI-upscaled to 9922 × 14032 pixels. Despite doubling both the width and height, the edges remain soft, with only minor improvements in this example.

Both images are displayed at approximately the same size using different zoom levels.

The takeaway: Upscaling a finished poster doesn't guarantee that blurry details will become sharp. It's usually better to upscale the original artwork before creating your design.

⓺ The recommended workflow

If your artwork needs additional upscaling, here's the workflow I'd recommend:

Generate your artwork → Check pixel dimensions → Upscale if needed → Inspect the quality → Import into Canva Pro or Photoshop → Create your poster → Export at the correct dimensions → Check the final file → Upload to PrintShrimp.

⓻ Final thoughts

Not every image needs additional upscaling. As Tom has mentioned in the classroom, he often uses Midjourney's Creative Upscale without further upscaling, and his posters print just fine. Midjourney's Creative and Subtle Upscale already produce higher-resolution images, which may be sufficient depending on the artwork and intended print size.

For example, a simple illustration with smooth colours and clean shapes may look great at a larger size, even with fewer pixels than our recommended targets. More detailed artwork may benefit from additional upscaling.

Larger posters are also generally viewed from further away, meaning small imperfections are less noticeable.

Remember: More pixels don't automatically mean better quality. A larger file cannot restore genuine detail that was never present in the original image.

!!! If you read this on smartphone, swipe left to reveal more photos.

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Image Upscaling: A Detailed Guide for Beginners