What is the appropriate size for publishing pixel art from retro games (MSX/Famicom, etc.)?

This is another niche article. When sharing pixel art from small retro PCs or retro games on social media, etc., the original size is too small, so it needs to be enlarged. I will consider what the appropriate image size is as of March 2025.

Aiming for pixel perfect

Famicom: 256x224, MSX1: 256x192, MSX2: 256x212, PC Engine: 256x224 (others). I will consider how to publish images of this size while keeping the dots crisp and accurate.

A well-balanced size

I will consider the viewer's perspective, with smartphones as the primary device and PCs as secondary. I am assuming social media, but I will not consider techniques specific to X (Twitter) for now. There are various smartphone resolutions these days, but basically, they should support 16:9 so that videos can be played. I will consider sizes close to HD 1280x720p or Full HD 1920x1080p. Considering holding a smartphone vertically, a width of 512px, which is 2x the 256px width, fits within 720px. It looks a bit small on a PC. Considering 1080px, it becomes 1024px at 4x. I missed 3x. Well, since pixel art images are landscape-oriented, let's lower the priority of vertical orientation and emphasize horizontal orientation. 3x fits within 720p, and 4x fits within 1080p.

On Note viewed on a PC, even at 3x, the width does not fit and is scaled down. 3x seems good for casual viewing. This is the first correct answer.

Full HD specialization

Considering video production and future higher resolutions, it seems fine to think about using the full capacity based on Full HD 1920x1080p. Here, the limit value changes depending on the model that is the source of the pixel art.

For vertical 224px heights like the Famicom and PC Engine, 4x is the limit. In the case of the MSX, 5x barely fits. It is even safer to fill the margins with black to make it Full HD size. And there is still room in the width.

Correcting the pixel aspect ratio

The four models mentioned as examples all have pixels that are wider than they are tall. Some commentary sites state that the Famicom has a 1.17:1 wide ratio but I subscribe to the theory that it is 8:7, or 1.143:1 (https://pineight.com/mw/page/Dot_clock_rates.xhtml. To be precise, the ratio is 1.14285714286:1 , and taking the reciprocal, the height is 0.875 times the width. MSX1, MSX2, and PC Engine can also be calculated with this ratio. Dividing the original image width of 256 by 0.875 gives a width of approximately 293 dots. Listing how the Famicom image size changes from 1x to 5x: 1x: 293x224 / 2x: 585x448 / 3x: 878x672 / 4x: 1170x896 / 5x: 1463x1120. 5x for MSX2 is 1463x1060, and 5x for MSX1 is 1463x960.

Famicom 5x slightly exceeds the top and bottom. The wasted space on the left and right is gone.

At this time, since enlargement that is not an integer multiple is included horizontally, blurring of the dots will occur if normal enlargement processing is performed. (Actually, it is blurred on a CRT monitor, but if you consider the appearance as pixel art, it is better not to have blur.) You need to choose an algorithm that leaves clear dots, such as nearest neighbor. The horizontal size of one dot varies depending on the location, but you won't notice it unless you enlarge it and stare at it. Emulators like webMSX also have horizontal enlargement by default, but you cannot tell that the 1-dot size is fluctuating. This is the second correct answer.

Using the full height

Since the width has been stretched anyway, let's try stretching the height to 1080px. In this case, Famicom: 1413x1080, MSX2: 1493x1080, MSX1: 1648x1080. The number of vertical and horizontal dots per pixel will be uneven, but if you don't mind that, this is the third correct answer.

I will also consider note headers. The note article header has a somewhat confusing vertical pixel count of 1920x1006, but if we take this as the maximum, the sizes would be Famicom: 1316x1006, MSX2: 1390x1006, and MSX1: 1535x1006, respectively.

The calculation is a bit tedious, but the required width is (Vertical Max * 293) / (224, 212, or 192).

Is it not okay to leave it small?

If you publish it as is and the viewer enlarges it, there is a risk that anti-aliasing will be applied, ruining the crisp look of the pixels. Even if you want anti-aliasing, you cannot control how it is applied, so it is better to upload a large image that you have applied anti-aliasing to yourself.

Regarding file size

While larger images consume more file size, that is the beauty of pixel art; since the number of colors is low and the patterns are not complex, compression is very effective. In the case of this header image, it is 24.8k at 1920x1006px. You can safely ignore it.

Well, in this article, I have summarized my thoughts on image sizes for sharing sharp, edge-defined pixel art, but in the next article, I will consider enlargement while taking into account the characteristics of CRT monitors.