Resizing / Upscaling Photos in Corel Paintshop Pro

Today I'd like to discuss resizing photographs, but in particular, resampling a photograph to a larger size.

As any seasoned photographer knows, you never use the digital zoom feature on a camera because the blowing up and cropping to size that cameras do, always results massive quality loss.

Professional photographers know that when you do need to enlarge a photograph for say, poster or billboard printing, or zooming in on your subject when you took the photograph from too far away, it's always best to use professional editing software.

The question is, how do they do this? How do you upscale photos to massive sizes without significant quality loss?

If you do a Google search you will find that people use basically one of two techniques and they tend to disagree on which technique works best.

The one camp basically says that you resize, from your original size, to the size you want, like 36 inches for poster size, with only one resize. In other words, you open your resize utility, select the size you want, and resize only once.

The other camp says that you should resize by 10% increments until you reach your desired print size.

Other than that the techniques are the same as I'll explain in a moment.

Ok good, so which camp is right, and who doesn't have a clue what they're talking about?

The truth is, both approaches work well, depending on what your final print size is going to be.

Corel's documentation on resizing says that you should only resize once, so they agree with the first camp, but is this the really the best way to upscale?

I've personally tested both techniques extensively and now I mostly stick to one but before I get into that, let's discuss a few basics about resizing.

Firstly, Corel's documentation states that you have to do all your editing first and then resize.
I disagree with this approach as it mostly causes unwanted artifacts in your final image. Any editing reduces quality and upscaling will always emphasize or increase any problem areas in your photo.

We are, after all, adding pixels to the photo which didn't exist before.

To get the best quality out of upscaling, we need to use the best quality photo possible, to start our upscaling process with.

Ok, so let's start by opening the photo we would like to upscale in Corel Paintshop Pro.

In taking this photo I didn't have my tripod with me. Also, this tiny bug was sitting in a difficult spot, very hard to get to and I was unable to get close enough for a true 1 to 1 macro shot. This means I had to crop the image in order to get the subject large enough and remove a lot of useless background detail.

The problem now, is this image has been cropped to a smaller size and I can no longer make a large print. I want to upscale this image, either to its original size or maybe even bigger so I can make a poster sized print.

Now back to the two camps on resizing, and here's the real truth of the matter.
If you want to only resize back to your original size, meaning you increase the image size by no more than 50%, then the "resize only once" option works just as well and it's quick because you only do the work once.

See below...

So you start by selecting the "Image" menu option in the top menu bar, and select "Resize".
This will open the resize utility.

On top, select the radio button that says "By Print Size".
The "Width" and "Height" options are linked, meaning if you change one, the other will update automatically, but only if the "Lock Aspect Ratio" check box is checked at the bottom. You want to always have this option checked, otherwise your photo will scale to unexpected dimensions.

Here I've increased the width to 15.5 inches, which will upscale the image by 45%, back to it's original size. Also, I always set the resolution to 350 pixels per inch because this is what you need when you want enough quality to make large prints.

Most graphics editors suggest that when upscaling, you should select the "bicubic smoother" algorithm. In Corel Paintshop Pro, as you can see from the above, you select bicubic under "Resample using", and then you have a slider where you can decide how much smoother or sharper you would like to go.
I find I get the best results by leaving the slider in the middle, on a setting of 50.

Alright, that's it, now you simply click on "Ok" and let Paintshop upscale your image.

You will notice that Paintshop has done a really nice job of upscaling your photo without any noticeable quality loss.

Unfortunately this technique only works well while you are upscaling by 50% or less. Any more, and the quality loss becomes noticeable.

In this case I want to upscale by 300%, meaning I want the image 3 times larger so I can get it to a size of 36 inches. For this, the incremental upscaling technique works best.

So now, open up the resizing utility again.

This time, select the radio button that says, "By Percentage".
The rest of the settings stay the same as per the previous technique.
There's no option to set the resolution to 350 pixels per inch so I always make sure that I export my photos from my RAW editor as 350 PPI Tiff files.

Go ahead and enter 110 in either the "Width" or "Height" boxes. Note that 100% is the original image size which is why you enter 110 to get a 10% increase in size.

Now when you click on "Ok", Paintshop Pro will upscale your image by 10%.

You now have to repeat this process until you get to your intended upscaling value of 300%, which in this case means I have to resize another 11 times.

This is a bit of a tedious process but luckily Corel Paintshop Pro has a shortcut. You simply press "CTRL + y", and Paintshop will apply the exact same resize again. Upscaling your photo by another 10%.
So here, I will press "CTRL +y" 11 times, until I get to the correct size.

Here's the result...

As you can see from the top ruler, my image size has increased from the original width of 3741  to 11741.
Quite a big step up with virtually no noticeable quality loss.

Well, there you have it, now you can go ahead with the rest of the editing you would like to do on your image.

Hope you enjoyed this post.

Happy editing.


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