How do I choose a good image from which to make a mosaic?

The devil is in the details. Images with less detail will require fewer tiles and thus fewer images to make the mosaic. The lion on the examples page has very little detail so I was able to create a very accurate mosaic using only 20x20 tiles. Contrast that with the Mona Lisa which required 30x40 tiles to make a convincing mosaic.

What is the Random Glyphs image source?

This image source picks a random letter (known as a glyph) from a random font on your computer and draws it in a random color over a background of a random color. While not as interesting to look at as tiles with images, they are useful if you do not have access to Google or a large collection of local images.

Can I load a list of Google Image terms from a text file so I don't have to enter them each by hand?

No, you can't load them from a text file, but you can save yourself the trouble of having to add the terms individually. If you enter a semi-colon separated list of terms they will be added as separate image sources.

How do I make my mosaics look better?

Images with more detail require more tiles (increase the number of tiles across or down.) In the examples below, notice how the woman's features and the bands of lace become apparent as more tiles are used.

Original	10 x 10	20 x 20	30 x 30	40 x 40

Another way to improve a mosaic is to add more images. It's good for each tile to have at least ten images to choose from, so for a 20x20 mosaic you should have at least 4000 images. For a 40x40, you need at least 16000.

When using Google, I typically start with keywords that correspond to the image (e.g. - bride, wedding and veil for the mosaics above) and then add color or texture keywords (e.g. - white, skin or lace) if the thematic ones were not good enough. Google seems to limit the number of images per search to about 800, so if you are searching for multiple keywords it is better to create a separate Google image source for each keyword, rather than OR'ing them together in a single search.

For the Random Glyphs image source, you just need to let it run for a long time. On a typical OS X system, there are 31 fonts with around 256 glyphs each. With 16 million foreground and background colors to choose from, there are 133 billion possible glyph images that could be produced. Even if your computer could match 100 glyph images per second, it would still take 42 years to look at them all. So don't wait too long...

Once I've got a good looking mosaic how do I print it?

You need to save your mosaic as an image file by choosing "Save As..." from the File menu. TIFF or PNG formt are probably best because JPG can lose some quality. You'll want to go with 300 dpi resolution and then play with the width and height. (When you change the width or height it automatically changes the other to preserve the size of the mosaic.) You can then print the image file by any of the following means:

• Print the image yourself if you've got a good quality printer and paper.
• Take the image file to a print shop, e.g. Kinko's.
• Upload the image to a photo sharing service (flickr, Shutterfly, etc.) and order a poster print.
• Add the image to your iPhoto library and order a print from within iPhoto.

What can I do if MacOSaiX tells me that my image is too large or crashes when I try to save as an image?

MacOSaiX can only handle saving images up to about 10,000 by 10,000 pixels. If there is not enough memory available to create the image then MacOSaiX will report an error or in some cases may even crash. If you need to create a larger image than this then you need to "divide and conquer":

• Split your original image into multiple pieces.
• Create a mosaic from each piece of the original.
• Save each mosaic to an image.
• Paste the images back together.

Version 3.0 of MacOSaiX will be able to handle much larger images without having to "divide and conquer".

Does MacOSaiX run on Windows? Linux?

No, MacOSaiX only runs on Mac OS X. If you want to create mosaics on these platforms then you can try any of the other programs listed on Wikipedia's photographic mosaic page.

What do I do if I get the "spinning pinwheel" when running MacOSaiX?

If MacOSaiX hangs for a long time then the only solution is to force quit. However, if you wish to help discover the cause of the problem then grab a sample of MacOSaiX before you quit it:

• Launch the Activity Monitor application. (It's located in Applications > Utilities).
• Select MacOSaiX in the window that comes up.
• Choose "Sample Process" from the View menu.
• Wait for the sampling to complete, click the save button and save the sample.
• Send the sample file to me at knarf@mac.com.

I'm very low on disk space after running MacOSaiX. How do I get it back?

There are three main places where MacOSaiX can use a lot of disk space:

1. The flickr and Google image sources keep copies of recently used images to make MacOSaiX run faster and to lighten the load on their servers. These copies can be safely removed by clicking the "Delete all Local Copies" buttons in the flickr and Google preferences in MacOSaiX. If you create a new mosaic that needs to use any of the deleted images they will be downloaded again.
2. There is a bug in versions of MacOSaiX prior to 2.0 when using certain QuickTime movies. An error message is repeatedly reported while MacOSaiX searches through the movies. Thousands and thousands of messages can be added to your console log, potentially using up many megabytes of space. To free up this space you need to remove the current console log file. It is located at Computer > Library > Logs > Console > 501 > Console.log (It may be a different number like 502, 503, etc.) You may lose some debugging information from other applications if you delete this file but it is the only way to reclaim the space.
3. MacOSaiX can use a lot of virtual memory. If you don't have much physical memory (RAM) or are running many programs at the same time then Mac OS X will use space on your hard drive as memory. This space is not always reclaimed when MacOSaiX quits. The only sure way to get it back is to simply restart your Mac.

How do "filler" image sources work?

Consider that you are a teacher making a mosaic from pictures of the students in your class. You have added a normal (non-filler) image source for the students' pictures and they get placed in the mosaic. However, even after all of the images get used there are still holes in the mosaic. To fix this you add a normal Google image source which fills in the holes but also removes some of the students' pictures. Those kids are not going to be very happy when they can't find their picture in the mosaic.

Filler image sources fix this problem by filling in any blank tiles but without removing any of the images already in place. You could think of filler image sources as existing in a separate Photoshop layer behind the main layer. Only in the places where the main layer is blank will you see the filler layer. So the teacher could add the Google image source as filler and it will fill those images in around the students' pictures without removing any of them. Happy teacher and happy kids!

For feature requests or bug reports send me a message at knarf@mac.com

Copyright 2007 Frank M. Midgley