Originally Posted by
John Chardine
Ah, an interesting question- counting bird flocks. I do this for a living and it's not easy!
We use several methods. Visual estimation as Artie suggests can be hit and miss but trained individuals can do a good job. We train people by throwing a known number of grains of rice on a table and having people estimate numbers. With practice they get pretty good.
A technique I developed with a colleague is to use Photoshop. Attached image illustrates method:
1. Create a layer above the image.
2. Choose a square pencil of certain dimension (usually 3 pixels x 3 pixels works well but depends on image)
3. In the new layer place a square dot of a certain colour over each target.
4. In Histogram, have Ps give you a pixel count of the dot layer. Divide pixel count by number of pixels in each square dot. In this case it was 1620/9 = 180 birds.
There are other methods I use but there's too much detail here as it is!
Incidentally Artie, I noticed that your image has lots of jpegs anomalies and see that it is weighing in at about 100k. I think the image would improve if you saved at close to 200k. What do you think?