| Brick with "master.jpg" loaded |
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A number of sample images have been included with the Brick program for demonstration purposes. These consist of a small "master" picture, master.jpg and four "sub-pictures": black.jpg, blue.jpg, gold.jpg, and pink.jpg. The master image is a simple drawing of a smiling face and the sub-pictures are blocks of colour that match their names. In the following exercises, we will demonstrate how to employ Brick in rebuilding the master from a small library of sub-pictures.
To begin, we must compile a library which contains statistics about the average colours in the images we will use to make up the master picture. From the Brick menu, choose "Library/Build Library". You are presented with a dialog box with a number of buttons.
The library is something you only need to build once, unless you wish to add new photos at a later time. Note: If you move your photos, Brick will be unable to find them until you return them to their original path! If you are building a library file from your own set of photos, this process may take a long time if you have a large number of images. A library of 3000+ images takes approximately 1 hour on a 166Mhz Pentium with 96Meg of RAM. You may cancel at any time by hitting the cancel button on the progress box which appears.
With a completed image library, the normal starting point for using Brick will be to select a master image. Choose the Master picture button on the main page of Brick. Using the file dialog, browse to the JPG file you wish to work with; in our example this will be "master.jpg". Brick will attempt to load your master picture and will display it if successful.
| Brick with "master.jpg" loaded |
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Brick will not let us proceed in building a mosaic until we specify what the output file name will be. Your mosaic will be built in the format of a TIF image. Due to the large size of an effective mosaic, Brick builds it piece by piece on your hard drive, and TIF is a convenient format for this process. If you find TIF an ackward format, use one of the suggested utilities to convert the finished mosaic to the format of your choice.
Press the TIF name button and enter a name and path for your finished mosaic.
The size of your mosaic file is determined by its resolution and dimensions. These can be set on the main page of Brick. The resolution of a typical colour laser printer available at most printing service providers is 400 dots per inch (dpi). A mosaic resolution of 200dpi is usually adequate for an excellent quality print and is a good trade off of file size versus resolution. To experiment however, Brick will finish faster with a lower resolution and smaller size. Try 50 or 100dpi, and dimensions of 1 or 2 inches when you are experimenting (Brick will not change the aspect ratio of your master).
Immediately below the Resolution, Width and Height fields, are the Ceiling, X, and Y subpics fields. The number of sub-pictures in the width direction is set by changing X. Similarly, the number of pictures in the height direction is set by determining Y. If you make X=Y, then the sub-pictures will have the same aspect ratio as the master image. Making one or the other larger will cause the sub-pictures to become distorted.
Ceiling is the number of times a given picture in the library may be used in a mosaic. Considering that a master divided into 40x40 sub-pictures requires 1600 images, normally we would allow a picture to be used multiple times. Before building a full size mosaic however, it is instructive to set the Ceiling to 0. When Brick runs out of unused pictures (immediately with Ceiling=0), it fills in the average colour at that position in the master image.
Try various values for X and Y with Ceiling set to 0. With X=2 and Y=2, our sample master is not very well reproduced. Increase X and Y to 4 or 8 sub-pictures and the "legibility" of the mosaic improves. This is a good way to decide how many sub-pictures should be in a large mosaic BEFORE setting your final resolution and size in inches. Working with a small resolution and size, and a ceiling of 0 will save time while you are experimenting. An 8.5x11 inch mosaic of a persons face is reasonably well represented by X=Y=40 sub-pictures. For best results, make sure your subject matter mostly fills the master image!
Hit the Build composite button to make the mosaic! The example images below make use of the supplied JPGs and a high ceiling value (200). Try reproducing these images and you may find your master picture has been included in the library file! How to remove an image from the library is described below.
 2x2 sub-pics |  4x4 sub-pics |  8x8 sub-pics |
When Brick finished working on a mosaic, the progress box will disappear and a small representation of the TIF composite will appear on the page. By clicking on this composite image, a close up view of each sub-picture can be obtained. This zoom dialog gives the option of removing the picture from the composite. If you do not like a sub-picture, this allows you to mark it as "unwanted" in your image library. Next time you rebuild the composite, it will not be included.
Library images can also be marked as unwanted through the "Library/Edit Library" menu. A dialog box will open which allows you to choose a library file and specify a path or individual photo to remove from the library. Similarly, entire directories trees or individual images can be re-added to the library (only images which have been previously marked as "unwanted" can be re-added in this way; new photos can only be included by rebuilding the library). Photo JPG files are in no way removed by Brick; the reference to them is simply marked as "unwanted" in the Brick library file.
Note: Large library files can take 5 to 10 seconds to load or save. Brick will open/save the library file before/after editing (ie. exiting Brick after clicking on a finished mosaic or using the Edit library menu).
