leads me to realize that the format coming out of vidcap.pyd is in BGR format, not RGB format like the Surfaces expect. Looking at the documentation for the Image.fromstring method, it says that putting a -1 at the end flips the image. Then looking at pygame.image.fromstring:
http://www.pygame.org/docs/ref/image.html#pygame.image.fromstring there is a flipped boolean. Use it. ;)
It does seem strange that frombuffer doesn't have a flipped argument, and I'm not sure why. Anyone else able to add some insight?
-Tyler
On Sat, Jun 13, 2009 at 9:35 PM, Ian Mallett
<geometrian@xxxxxxxxx> wrote:
Hi,
So, I'm trying to get VideoCapture working with PyGame. I've modified the standard VideoCapture.py file to make it simpler and easier to read. I've attached it as well as my program, main.py.
VideoCapture.py defines a class Device. Device has two functions that I'm concerned with: .getBuffer(), which returns (string_data,width,height), and .getImage(), which returns a PIL image made with .getBuffer().
I'm trying to get a PyGame surface from all this. Every code sample I've seen converts the PIL image (returned from .getImage()) back into a string, and then makes a PyGame image with pygame.image.frombuffer(...):
im = Camera.getImage()
image = pygame.image.frombuffer(im.tostring(), im.size, im.mode)
Though this works nicely, it seems terribly inefficient--VideoCapture.py takes the data as a string from .getBuffer(), and makes a PIL image. The main, main.py, must then change this PIL image back into a string again, and then make a PyGame surface from that. (Basically: STRING->PIL->STRING->PYGAME). This setup doesn't fly realtime. Moreover, it requires an extra dependency, PIL.
So, I tried just converting the original string from .getBuffer() directly into a PyGame surface. (Basically: STRING->PYGAME):
data = "">
image = pygame.image.frombuffer(data[0],(data[1],data[2]),"RGB")
But this has problems. It doesn't crash, but the image is upsidedown and the red and blue color channels appear to be flopped. I tried fixing it with surfarray, which didn't work. Then I tried finding what was wrong, and got inconsistent results.
How can I get the second method (method 2: STRING->PYGAME) to look like the first method (method 1: STRING->PIL->STRING->PYGAME)? main.py lets you switch back and forth (press 1 for method 1, 2 for method 2).
Ian