Introduction
In 2020 LEGO introduced a new theme called LEGO Art. The sets released in this theme are a departure from typical LEGO sets that contain a wide assortment of LEGO elements. Instead, the LEGO Art sets mainly consist of a sizable number of 1×1 round plates or tiles in various colors. Also included are new 16×16 Technic bricks that can be used as baseplates.
These bricks can be joined together using Technic pins to create a large flat surface that the 1×1 elements can be attached to. When you finish putting together one of these sets (using the instructions that are provided), you have a two-dimensional artwork portrait of an iconic real-life personality or a character from pop culture (the first batch of sets included portraits of Marilyn Monroe, the Beatles, Iron Man and Darth Vader).
The builds you can create with the LEGO Art sets would generally be classified as LEGO mosaics. While this new theme is the first major foray LEGO has made into mosaics in their official sets, mosaics have been fixtures in the building repertoires of LEGO builders for quite a long time. In the early days of LEGO, mosaics had to be designed by hand and this greatly limited their size and complexity. But the advent of digital images and modern computers made it possible for builders to turn any picture of their choosing into a LEGO mosaic using software.
In this chapter, we will take a closer look at the different types of LEGO mosaics and how they draw inspiration from traditional art forms. We will then get an overview of the steps involved in the creation of a LEGO mosaic (these steps are typically carried out under the hood of the software programs we use for this purpose). Hopefully, a better understanding of the inner workings of LEGO mosaic software, its capabilities and limitations, will enable us to use it more effectively.
Let’s start with the basics. A mosaic in the traditional sense is a picture or pattern created by arranging together small colored pieces of stone, glass, etc. As the name implies, a LEGO mosaic is a mosaic created using LEGO pieces. Unlike traditional mosaics where the pieces of stone or glass need to be cut to size and mounted on some kind of substrate using glue, we can create a LEGO mosaic simply by attaching LEGO bricks, plates, tiles and other elements to one or more baseplates.
The typical starting point for most LEGO mosaics is a digital image. Digital images may be ubiquitous on our smartphones and computers, but it is helpful to understand how the data in an image file (say a JPG, PNG or BMP file) is organized. An image is basically a 2-dimensional grid of square picture elements (or pixels) each of which has a particular color. All the pixels (especially when there are enough of them) blend together in our brains to create the illusion of a continuous image with light, shadows, shapes, colors, and textures that resemble what we see in the real world.
The pixel grid in an image is analogous to the regular square grid of stud locations in the LEGO system. And so, why can’t we just map each pixel in the image to a LEGO 1×1 brick or plate in the right color? Unfortunately, it is not always as simple as that. In fact, as we will see, a LEGO mosaic can at best only be a very crude approximation of the original image. There are two reasons for this – the resolution of the image and its color depth.
Resolution
The resolution is the level of detail that is captured in the image, and it is proportional to the number of pixels that it has (the more pixels that an image has, the more details it is able to capture). You normally cannot see the individual pixels that make up a digital image (unless you zoom into it all the way using a photo editor like Photoshop) and that is because of the sheer number of pixels that make up a typical image.
The earliest digital cameras from the late 1990s produced images with what would now be considered a very low resolution – typically something like 1024×768 pixels which is under 1 megapixel (a commonly used unit that is equivalent to 1 million pixels). But if we translate that to LEGO where the smallest element we can use to represent each pixel is a 1×1 brick or plate (with a footprint of 0.8×0.8 cm), we would end up with a LEGO mosaic that is 27×20 feet wide!
So clearly, we have to reduce the resolution (number of pixels) of the source image dramatically before we can represent it using LEGO. For instance, if we downsize the 1024×768 image by a factor of 8, we will end up with 128×96 pixels. This would work out to a large (but more manageable) mosaic that is 40×30 inches wide. This process comes with a significant loss of fine detail in the resulting LEGO mosaic. It is also more challenging to create the illusion of a continuous image because it is hard not to see the individual pixels that make up a LEGO mosaic. It’s no wonder that most LEGO mosaics don’t look very good when viewed up close. You always have to step back a few feet to get the intended effect of the mosaic.
Color Depth
Next, we look at color depth. In a typical color image, each pixel has 8 bits of data for each of the 3 primary colors – Red, Green and Blue. By combining these 3 primary colors in the correct proportion, we can represent more colors in the color spectrum than humans can actually perceive. Each bit can have two values (0 or 1) and so 8 bits allow us to represent a total of 2x2x2x2x2x2x2x2 = 256 total values (0 to 255) for the intensity of each primary color and together we have a total of 256x256x256 = 16.7 million possible combinations each of which is a distinct color in the color spectrum. When we create a LEGO mosaic, we have to map those 16.7 million colors to the 40 or so commonly available colors in the LEGO color palette.
As you can imagine, this also results in a significant loss of the detail in the image that comes from the gradations of light, shade, and color. It also creates limitations on the kinds of images that can be represented well using LEGO mosaics (for instance, images that have subtle gradations of a small number of colors do not always translate to LEGO very well).
Types of LEGO Mosaics
i) Studs-out Mosaics
Studs-out mosaics are the most common type of LEGO mosaics. They are created by attaching LEGO bricks or plates to a LEGO baseplate with their studs facing out. Each pixel is represented by a 1×1 brick or plate which happens to have a square footprint. One advantage of using regular bricks or plates is that they can be combined into bigger pieces when the mosaic pattern allows it (when two or more neighboring pixels have the same color) for a reduced overall piece count. However, some like to avoid having blocky pixels in their studs-out mosaics, preferring instead to use 1×1 round plates or tiles (as in the LEGO Art sets) at the expense of a higher piece count.
ii) Studs-up Mosaics
One way to increase the resolution of LEGO mosaics (albeit in just one dimension) is by building them with their studs up. LEGO plates are thinner counterparts of bricks and they are thinner by a factor of 2.5 compared to the regular stud dimension.
And so if we stack LEGO plates such that the design of the mosaic is created by plates as seen from their side, we can pack more detail into the same overall size. One obvious downside is that we now have to deal with rectangular pixels. Studs-up mosaics are also more challenging to build practically speaking, because we are creating the mosaics by stacking plates rather than attaching them to a baseplate. This can lead to stability issues especially if the design of the mosaic does not allow for the plates to be overlapped correctly for a stable structure (in most cases we have to make the mosaic 2 studs deep allowing longer plates to be attached horizontally behind the mosaic for improved stability).
While studs-up mosaics are usually built using LEGO plates, some may prefer to use bricks instead, which results in larger pixels that are still not square in size (given that a 1×1 LEGO brick is slightly taller than it is wide).
iii) Lenticular mosaics
A lenticular mosaic creates the illusion of an image that changes with the viewing angle. Lenticular mosaics (along with lenticular wall displays) take their inspiration from a 16th century invention called tabula scalata (or “turning images”). A tabula scalata has two images divided into vertical strips and printed on different sides of a corrugated surface allowing the two entirely different images to be seen depending on the viewing angle.
Back in 2010, AFOL Chris Doyle stumbled upon the idea of creating lenticular LEGO mosaics using cheese slope pieces. He placed the cheese slope pieces such that the slopes faced opposite directions (left vs. right) in alternate columns. This created a corrugated surface like what is used in a traditional lenticular mosaic and allowed two distinct images to be combined into a single LEGO mosaic (with only one image visible when the mosaic is viewed from either the left or the right side).
Figure X shows an example of a lenticular mosaic with two different images that can be seen depending on the angle that the mosaic is viewed from.
iv) Other types of mosaics
There are several other types of LEGO mosaics created using one or more specific types of LEGO pieces. These usually represent patterns (geometric or otherwise) instead of actual images. These are typically created by hand and not using software (except for 3D mosaics where we may use something created using software as a starting point for the design of the mosaic).
3D mosaics
As the name implies, 3D mosaics aim to create an illusion of depth in addition to the picture or pattern that they depict in the normal 2 dimensions. This is achieved by stacking multiple layers of bricks or plates in certain areas of the mosaic. It is also possible to create a mosaic using LEGO elements such as Minifigures as shown in Figure X instead of regular bricks or plates.
Some LEGO artists even create mosaics that depict a familiar image when viewed from a distance, but upon closer examination, it turns out that these mosaics are built out of completely random LEGO elements (including unconventional ones like wheels, gears and so on).
Isometric pattern mosaics
The 2×2 triangular tile is a relatively new addition to the LEGO catalog (it was introduced in 2018). However, it opens up a lot of new possibilities for mosaics when it is combined with regular 2×2 square tiles. These 2×2 tiles can be used to create a wide range of interesting mosaics that represent isometric geometric patterns (patterns that do not have the perspective distortion that you would normally see in a 3D representation).
Cheese Slope Mosaics
This style of LEGO mosaics popularized by AFOLs like Katie Walker takes advantage of the geometry of 1×1 cheese slope pieces to create some unique mosaics.
One tricky thing about cheese slope mosaics is that these pieces are not really attached to anything in the mosaic. Instead, they are just pushed together tightly and held in place by an outer frame built out of bricks or plates.
Headlight Brick Mosaics
Headlight bricks as we have seen in Chapter 5 can be joined together in quite a few different ways. Headlight brick mosaics exploit this to create a lot of interesting patterns using headlight bricks. Seen in Figure X is one such pattern inspired by the work of AFOL Brendan Powell Smith.
Steps Involved in Creating a LEGO Mosaic from a Digital Image
i) Image Resizing
We have seen how a typical digital image has too many pixels for it to be represented as is, in LEGO mosaic form. The first step to creating a LEGO mosaic is resizing the image to match the size (in pixels) of the LEGO mosaic that we are planning to build. We have to take care to ensure that our original image has the same aspect ratio (proportions) as our mosaic (this can be achieved by selectively cropping the image) to ensure that we don’t distort our image when we resize it.
If we want our LEGO mosaic to be say 128×96 studs wide, the image will first have to be resized to have 128×96 pixels at least in the case of a studs-out mosaic. Things get a little trickier for studs-up and lenticular mosaics. The pixels in studs-up mosaics are rectangular and so we can fit more of them (2.5 to be exact) in 1 stud dimension vertically. And so, the image will have to be resized to 128×240 pixels (240 is 96 times 2.5) and this way when we build the mosaic using the sides of 1×1 plates (which are much wider than they are tall), the completed mosaic has the correct proportions. In the case of lenticular mosaics, we are dealing with two different images that need to be combined. We will need to resize each image to have half the width (in terms of pixels) of the finished mosaic (which works out to 128×48 in our example) and interleave the columns of pixels in the two images for a total size of 128×96 pixels.
There are several different algorithms that can be used to resize images. Some software programs that create mosaics give you the option of choosing the algorithm to use. Something like Lanczos Resampling should work well enough in most cases but if you are starting with an image (such as a cross stitch pattern) that already has a pixelated appearance, a different method like Box Resampling can prove to be useful. This method works by breaking the original image into boxes (which can correspond to the “pixels”) and averaging the colors inside each box.
ii) Color Quantization
Color quantization is the process of decreasing the color depth of an image (or reducing the number of distinct colors that it uses). This is an important step for the creation of the LEGO mosaic because it involves going from an image that has millions of distinct colors to one with the 40 or so colors in the LEGO color palette. The method used for this step has a great bearing on how well the LEGO mosaic resembles the original image.
The simplest method (and least intensive computationally) is to remain in the RGB color space (which is essentially a 3-dimensional space with the three primary colors Red, Green and Blue making up the 3 dimensions) and for each color in the original image, find the nearest neighbor in the more limited color palette (the LEGO palette this case). But this method doesn’t always align with the way humans perceive similarity between colors.
An alternative is to use the L*a*b* color space which was designed to better represent the way humans perceive color. It is also a 3-dimensional space where L* or lightness is an achromatic component that represents shades of grey and the a* and b* components represent the proportions of the primary colors (red, green, blue and yellow). By converting all our colors from RGB to the L*a*b* and using the Delta-E algorithm to compute the difference between colors in the L*a*b* color space, we can create LEGO mosaics that have a closer resemblance to the original images that we started with.
iii) Dithering
While there is no good way to counter the loss of resolution that the creation of a LEGO mosaic entails, we can use dithering to somewhat alleviate the loss of color depth. Dithering is a technique that allows an image with a wide gamut of colors to be represented using a much more limited color palette. It involves arranging pixels in the available colors in such a way that they collectively emulate the colors that are missing. This technique was used historically in early computer displays that had very limited color palettes. Inkjet printers to this day use halftoning which is a form of dithering (in this case the individual dots or pixels can vary in size).
Here is a simple example that may help illustrate the concept of dithering – suppose we want to display shades of gray and only have the option of using either black or white. Neither black nor white can really pass for gray and yet if we have enough pixels to work with, we can create checkerboard patterns with the right proportion of black and white pixels that combine to create the illusion of various shades of gray. In the same way, if our original image includes colors that do not exist in the LEGO palette, we can arrange LEGO pieces in the available colors in such a way that they combine in our brains to create the illusion of seeing the colors that are missing.
Figure X shows an example of two mosaics based on the same image created without and with dithering. As you can see, dithering greatly helps reduce blotchiness caused by the limited LEGO color palette not being able to accurately represent subtle gradations, especially in skin color.
