I have tested Topaz Gigapixel AI before and concluded that it is the best image resize software. I now wanted to give it quite a stern challenge. How would it fare going up against a  top-rated teleconverter such as the Canon EF 2x Extender, Mark 3?

The extender

Canon’s 2x extended attaches to some of their high end lenses and effectively doubles their focal length. This extender has been tested quite extensively on the Web, with the consensus being that it is very good. It’s not as good as buying a bigger lens but it offers far superior quality to cropping and upsizing an image. It is also much cheaper than buying a bigger lens.

The extender has a few disadvantages:

• The extender lowers image quality a little
• It ‘loses’ two stops of light
• Extenders and teleconverters can affect autofocus speed

I used the excellent Canon ef 200mm f/2.8L lens on an EOS RP. The RP’s autofocus seemed untroubled by the extender- Canon’s mirrorless autofocus technology is different to DSLR’s.

The camera was tripod mounted, and I used a remote release. This was an indoor shot. Here are small versions of the two images. The version with the extended is on the right:

EF 200mm and 2x Extender

Obviously, the version with the extender looks like a cropped version of the image taken without it. That’s what the extender does – it doubles the focal length and narrows the field of view. What is the quality like of both images? Here’s a 100% view:

EF 200mm plus extended 100%

I have applied no sharpening or post processing to these images.

The test – Gigapixel AI vs the Extender

First, I took the image from the 200mm lens and enlarged it to 200% using Affinity Photo and compared it to the version with the extender:

Affinity (right) vs the Extender (left)

Affinity’s enlargement is not as sharp or as detailed as the version taken with the Canon extender.

Now I enlarged the native 200mm picture using Gigapixel AI. Here is how Gigapixel AI compares to Affinity:

Affinity (left) vs Gigapixel AI (right)

Gigapixel AI is the winner here. It is much sharper.

But now for the crunch – how does Gigapixel AI compare to the Canon 2x Extender:

Extender (left) vs Gigapixel AI (right)

Colour differences aside (caused by the auto white balance being influenced by the background in the wider picture) I would say that there’s not a lot in it between the two! Maybe Gigapixel AI is a little sharper in places. But it adds sharpening to the resize process.

I now gave both results some identical post processing:

Post-processing applied. Gigapixel AI (left) vs Extender (right)

After post processing, the Canon Extender image has similar sharpness to Gigapixel AI’s and is a little cleaner. You can see a few artefacts around the leaf edges in the Gigapixel AI version, although they are nothing to worry about. Viewing this image at 100% on screen is the same as viewing a 48 inch print close up. These flaws are meaningless when the image is viewed normally.

Conclusion

Gigapixel AI can produce results almost on a par with one of the best teleconverters/extenders available today. That is no mean feat. Compared to the extender, Gigapixel AI’s advantages are:

• Cost – Gigapixel AI is currently $99 USD. The Extender costs $429.
• Gigapixel AI works with every image you take. This Extender only works with certain high end lenses. Cheaper, 3rd party teleconverters are available that work with every lens but they are not as good quality.
• Gigapixel AI does not crop your images, the Extender does (in the sense it narrows the field of view)
• Gigapixel AI’s quality is almost as good as this very expensive extender. It will beat lower quality teleconverters
• You can apply Gigapixel AI later, if you forget to take the Extender you cannot apply it later
• Gigapixel AI weighs nothing, does not require using a tripod, does not affect autofocus and so on

The Extender’s advantages are:

• Slightly better image quality
• No need to spend time in a resizing program later
• You can use Gigapixel AI on its images, enlarging them still further

I don’t think Gigapixel AI makes the Extender redundant – wildlife photographers and bird photographers use them to gain extra reach without too much loss of image quality. The point of this test was to see how well Gigapixel AI could do against one – pitting a computer enlargement with an optical one. On paper, the optical enlargement should be a clear winner and against ‘regular’ image resizing methods it is. Against Gigapixel AI its advantage is minimal.

Gigapixel AI has done really well here, proving it to be an incredibly high quality image resize program.