Finder - how to match multiple sub-images within a captured image --- currently not possible

This is principally not possible with the current implementation: you can only use one level of find operations with a Finder() and you cannot restrict the Finders find operation to a subregion of the given image.

With this sequence of primary and secondary find operations on a real screen, with every find, there will be made a new screenshot and internally a new Finder(screenshot) for the respective area/subarea.

This does not happen in your Finder based solution with
current_match.find( field1 ) (which should be current_match.exists( field1 ), to make the if work ;-)

current_match is a region in the image, relative to its top left corner, but with current_match.find( field1 ) it is used as coordinates relative to the screen (the match currently does not "know", that it was made from a Finder(image).find() operation).

So if you want to solve this with a captured image, then you have to use Finder().findAll() for all objects and compare their coordinates, to find out, wether one match lies inside of another match (version 1.0.0 has the respective functions like region.contains(another_region) )

I think your approach is very interesting and Sikuli should have the possibility, to use a stored image the same way it uses a screen.
I put it on the request list: use image as a virtual screen

Thank you for your quick response!

I looked through the source code and noticed the following Finder constructor:
          public Finder(String imageFilename, Region region) throws IOException

I tried to use it with the following (modified) algorithm with no luck:

full_block = Pattern( "image1.png" ).similar(0.70) # image of block to find
field1 = Pattern("subimage1.png").similar(0.95) # a sub-image of image1.png, can uniquely identify the block
field2 = Pattern("subimage2.png") # sub-image of image1.png, a field to ignore, we won't do anything with it
field3 = Pattern("subimage3.png").similar(0.95) # sub-image of image1.png, important field (can exist in multiple blocks, but we're checking to see if it exists in this block)

f = Finder( "path\previouslyCapturedImage.png" )
f.findAll(full_block) # search previouslyCapturedImage.png, will return multiple matches
matches = []
while f.hasNext():
      matches.append(f.next())
f.destroy()

for current_match in matches: # Matches should now contain multiple "Match" objects which inherit from "Region"
      f2 = Finder("path\previouslyCapturedImage.png", current_match) # Would hopefully act as only the area defined by current_match
      if f2.find(field1): # Pseudo code if statement, field1 is high-similarity and unique so it should only exist in one of the matches
             if f2.find(field3):
                     print "Correct Information Found"
             else:
                     print "Incorrect Information Found"
             break
      else:
             # no match on unique identifier field 1, this means current_match is a different block, so skip to the next one
             continue
     f2.destroy()

Yes, there is such a constructor,but this is not used as you think and does not work like you thought it would work (it is only used, to recalculate the matches back to screen coordinates, that are used with a restricted find on a screen's smaller region).

As I said, on a given image it is currently not possible to restrict the search to a region within the given image.

The easiest way, to solve your problem would be, to display the image with a viewer on the screen and act on it normally.

The other more complex method would be to make findAll for all patterns with your Finder(image) and compare the match coordinates.