Extract image

  1. Open PDF in Acrobat or other PDF viewer and set zoom at the level where all details intersting you are decently visible. You should take into account resulting image size (for example, if your screen has resolution 1024X768 and the map scrolls up to 8 screens horizontal and up to 5 screens vertical, its projected size is:
    (8hscreens*1024pix_per_h)*(5vscreens*768pix_per_v)*(8bits_per_byte/4bits_per_pix) = 15Mb ,
    so, you may need to find compromise between detailedness and size).
  2. Set map to the left upper corner and consecultively copy each screen of it to your graphics editor. Do like following:
  3. Once you finished grabbing individual screens, you need to crop them of off user interface decorations, so only map graphic remains. Be careful to do it precisely: do not leave decoration's border and do not chop map's graphics. Setting zoom at 200% or higher is helpful. Some graphics editors allow to repeat operations on new images: once you set crop frame properly, you can apply it to each image with just several mouse clicks. If your editor supports this capability, as it can save you some effort.
  4. Finally, you need to fit all the screens into single map image. Usually, you do this by creating new image of required dimensions (you know how to calculate them), and copying the screens one by one there, aligning one properly before proceeding with the next. Again, appropriate zoom is helpful. You should keep in mind that most viewers scroll with negative reserve, leaving in each screen narrow strip of previous one, so you should not just make sure that there is no white space between screens, but that they are really align perfectly. This is not really hard with maps, as objects on them usually have sharp borders. In short, use your eyes as guideline. Last note: when you are really close to perfect hit, it is better to do final movements not with mouse which is not very precisise, but with cursor keys, which usually moves object by single pixel.
  5. Once you have done fitting screens into single map, you may want to crop extra border, if any. Well, now you have raw map image. What is left before you can use it with MapMap - converting the map to 4-bit format. Go on with Preparing image for use with MapMap Howto, which starts where this Howto ends.

Extract objects


  • (c) 2002 Paul Sokolovsky