SD HiRes fix vs SD upscale.

Hi there!

Generating images in higher resolutions is a very resource-intensive and time-consuming process for a video card. Therefore, images are often upscaled to a higher resolution instead.

What is the main difference between HiRes and SD upscaling? They operate in completely different ways.

HiRes generate images in a higher resolution right after generating them. This preserves the original image without adding any artifacts, but it also limits us in terms of video memory, as we generate up to 1.25-4 times bigger image than before.

Let's take a look at some examples. We'll generate an image without any details. We can see all the issues with the low resolution, especially when it comes to houses - their shapes are very distorted.

Original Resolution: 960 x 536.

Next, let's generate the same image using HiRes.

Resolution: 1920 x 1080.

You can see an immediate improvement in the quality and detail of the image, which is very close to the original one. The houses have changed for the better in particular.

But what is an SD upscaler and how does it work? It divides the original image into smaller tiles and generates each tile separately. After that, it combines them into one final image. What are the advantages of using an SD upscaler? Firstly, because we generate many small images instead of one big one, we don't need a lot of video memory. This is good news for those with limited resources. Also, because we can generate images in any resolution, we get a lot more detail. However, there are some drawbacks. If the tiles are too different from each other when combined, you can see lines where the tiles meet. Also, if we change the image too much, it will look more different from the original and there may be more artifacts.

Let's put this into practice and see how it works. Let's throw the original image into img2img and see what happens when we use the SD upscale tool.

Resolution: 1920 x 1072.

Tiles Resolution: 800 x 800.

You can immediately see how the picture has changed, with how many new details having appeared.

You can see the stems of grass blades, the relief on the mountains, and the houses taking on a more normal shape. However, unfortunately, some artifacts have appeared. The first artifact is a black spot on the field, followed by a stone that has become a bush, and finally, an obvious joint in the tiles at the second house.

In conclusion, HiRes Fix and SD Upscale have their own strengths, but there is no one perfect tool for increasing resolution. The choice of tool always depends on your specific goal and needs.