Prior to showing the source image colours, some pre-processing can be done: contrast and saturation, dithering, and colour quantisation (or: reducing the amount of colours).
After the source image is processed, the colour matching starts. There are several colour matching engines, where for some engines also the colour space can be chosen ('Adobe RGB' or 'sRGB' ).
Finally, all the output can be saved in two distinctive files: a photoshop file (.psd) with one colour in every layer, and the blueprint data (.xls) which all the colours in codes, just as the normal output excel blueprint file. There is a restriction on the amount of colours (in excel): 56. With black and white as the reserved colours, therefore the maximum amount of colours in the colour match is 54. The user can now change each colour by selecting a different brick palette colour for each colour in the source image. The result is immediately reflected in the right image.

Many source images have hundreds of unique colours. When no restrictions are set on amount of colours, the analysis can not create a colour match proposal. For that reason the checkbox 'Set maximum amount of unique colours' is required. The default is 24, quite a good amount for quite decent colour matches.

Image analysis

1.The 'Analyse source file' button. By pressing this button the initial analysis is done of the current source image. At start all the data is still empty, and is only filled after the first analysis is completed. This button is basically a manual analysis button, because many other parameters will automatically update the result.

2.When an analysis is made, it takes some application parameters and settings as input. One of these is the selected colours from the current colour palette. This palette is the same as shown in the normal application window. When colours are unchecked, these colours will not be taken into account for a new analysis. By checking this box all the colours are reset. It's the same effect as the 'Reset' button in the normal application window.

Colour matching engines

3. The colour match engine. This is the engine to match the brick palette colours with the unique colours in the source image. The general approach for each colour model is to compare the colour values (e.g. RGB, HSL) with those of the brick colour palette. The colour with the least difference is then selected as the replacement ('match') of that source image colour. There are 6 colour engines:

4. The checkbox to activate the maximum amount of colours limit, and the spinbox to set the actual limit. The maximum value is 54, as explained above.

5. The colour space of the CIE, Hunter and XYZ colour matching engines. There are two options: 'sRGB' or 'Adobe RGB' . These colour models are used in e.g. Photoshop (and Windows) to standardize colours of images, and should be device independent. The latter has about 40% more colours in its gamut, and will therefore provide different colour matches (not always necessarily better!).

Dithering of the source image

Image dithering is the approach to create colour noise to avoid bands of similar colours. In image editing applications, it's also used to elegantly reduce the number of colours in an image. The effect is clearly demonstrated with inkjet printers: with only 4 (or 6) colours almost every colour can be created. The individual colour pixels are mixed in such a way that the overall colour impression is excellent (to the human eye). We use dithering for two purposes: to get rid of bands of colours, and to reduce the amount of colours while maintaining the same colour impression. Although there are three parameters to set, not all parameters can be combined (you will notice it: nothing changes), and it's almost impossible to predict what the effect will be for each type of image. It's a kind of experimenting journey which dithering (and if) you prefer, and which colour matching engine will provide that great result.

The dithering has three parameters:

• 6. Pixel depth. This is the characteristic of how each pixel in the image must be treated. The choices are 'Palette colour' (24 bit colour depth: we skip the colour matching step by doing this directly in the dithering step, left and right image are therefore identical. Slow but very accurate), 'Original colour' (24 bit colour depth: a true dithering is done, using the original source colours), 'Grayscale' (8 bit colour depth: the image is converted into a grayscale image with 256 shades of gray, and then dithered), and 'Black and white' (1 bit colour depth: only two colour are used in the dithering process).
• 7. Palette type. This sets the type of colour replacement during dithering. Choices are 'Median cut' (the average or 'median' of the surrounding pixels is selected as the representative colour), 'Fixed BW' (only black and white pixels as output), 'Fixed halftone' (the output will attempt to create an image with 8, 27 or 64 colours only) and 'Fixed gray' (the output will attempt to use 4, 16 or 256 shades of gray pixels). The colour conversion for gray dithering is unexpected, since it's looking for gray pixel matching replacements, where the only parameter is depth of blackness.
• 8. Dithering type . This determines the shape of the dithering. Choices are 'Solid' (practically very little colour diffusion, and bands of colour still exist), 'Ordered' (in a 4x4 pixel matrix the colour are evaluated. less banding will occur), 'DualSpiral' (in a 4x4 matrix pixels are evaluated and clustered together, or removed, depending of the similarity of each these pixels), and 'Error diffusion' (pixels are replaced with pixels of a different colour, 'diffusing the colours', while also the amount of colours is reduced. This resembles the inkjet printer effect the most).

Colour replacement

In the table of the right you find three columns, each serving a specific purpose.

• 9. The source RGB. These are the original colours (maximized to 54) of the source image. The RGB value is provided as a reference. These are not the brick palette colours.
• 10. The selected matching colours of each of the source image colours. These colours are part of the brick colour palette. In some cases the match is perfect, while other matches are not very good. It depends on the colour matching engine what colour is finally selected.
• 11. The manual colour selection. When clicking on the third column, two things happen: all the pixels with the selected colour is highlighted in the source image (dotted 'moving' lines), and a dropdown box is shown. When you want to change colour with a different one, you can now select any colour from the brick colour palette. The change is immediately reflected in the image on the right.
• 12. Two additional options are provided: show the selected colour (the 'moving dotted lines') and 'Live update' of the colour change.

Analysis output

15.The output of the source image analysis can be saved as a Photoshop file (.psd) where all the pixels of each colour is saved in a layer in that file. Since the maximum amount of colours is 54, also no more than 54 layers will be created in the Photoshop file. Secondly, the same information can also be saved in an Excel spreadsheet file (.xls), showing the blueprint numbers and colours.

16. Similar to 15, also the output of the matched colours can be output. This is very similar to the spreadsheet output of the normal application interface.

Feature B. Creating a new colour brick dataset from scratch

In some cases you have special colours in mind and deviating bricks, which are not found in the Bricklink database which is installed in Legoaizer. In such a case you like to create your own dataset with colours and bricks. There is one way of doing it, starting from a Bricklink database, and then exit, but this will very likely fail, since the input format is very sensitive to errors.

We have now provided a very easy way to create a new dataset from scratch. You can the new data set interface from the menu bar > 'Colour table' > 'New colour/brick table'. This will open a very simple interface with just a few controls (see picture above).

The two little arrows on the left indicate the size of the table. It starts by default with 2 colours and 2 bricks (1x1 and 1x2 studs). These arrows will increase or decrease the amount of colours and bricks.
The two radio buttons indicate what kind of table you want to create: a brick table or a Beads table. The only difference is that in a Beads table only one type of brick is allowed: 1x1. When you try to create a Beads table with more than one brick it will warn you.

The table in the window has 4 fixed columns: the colour name (double click and type the colour name), the red, Green and Blue colour parameters (between 0 and 255), and at least one the brick size. More bricks are possible, more colours as well. There is no limit to the size of the table. Perhaps a practical size will hamper you a bit. The values under the brick reflect the cost of each brick-colour combination, and must be in the same value range as the one that is currently active in your application (menu > 'Preferences' > 'Other settings' > 'Currency x 100'). The brick sizes must be unique (errors may occur when you have identical brick sizes), and always start with the lowest amount of studs (so: 1x2 and not 2x1). To set a colour value a simple spin edit will show in the cell you select. You can use the up-down arrows to quickly set the value, or type in number between 0 and 255 (R, G, and B are provided in bytes).

When you are ready make sure all the brick values are available, and the brick names on top of the values are correct. Only the column that has a brick value (or rather: no text found) is taken as a table value. Then press the 'Save table as' button and provide a name of the file. The file extension is always .xml, and there is no need to provide it (automatically done). The table is not automatically active, only passively saved. To change table, follow the usual approach. Only when the table is found valid the new table will become active.