PAD L1 updates

[woodbe]

Based on the work for the PAD-L2, this is the update for the PAD-L1 changes for the fingerprint

[woodbe]

This needs work on how to take a latent print I think, and we probably need some additional materials based on that. Any new materials should be added at M.5 or above and then we adjust the L2 materials based on that.

[woodbe]

This will close #90, close #89, close #88

[woodbe]

@gfiumara @gregott Please check line 122 in the Overview about whether or not the image should be flipped when using a camera. I know it should when using the scanner, but I think if I'm using the camera to image the latent print, I don't want to flip it because I'm taking it flipped already by viewing it from the opposite side.

[gregott]

@gfiumara @gregott Please check line 122 in the Overview about whether or not the image should be flipped when using a camera. I know it should when using the scanner, but I think if I'm using the camera to image the latent print, I don't want to flip it because I'm taking it flipped already by viewing it from the opposite side.

I believe fingerprint scanners provide the same perspective as you get from an inked fingerprint on the old-fashioned cards. In other words, the image from a scanner will look just like the image from a latent of the same finger (excepting noise, of course). If this is true, the scanner image will need the same processing steps as a photo of a latent.

The only exception would be if you are collecting latent prints from a dark surface and are using white dusting powder. The assumption with scanner images is the ridges are gray and the valleys are white. When binarizing the scanner image the ridges become black and the valleys stay white. For latents on dark surfaces with white dusting powder, the ridges will be white (light gray) and the valleys black (dark gray) before the binarization step. The evaluator will want to take care to end up with black ridges and white valleys after binarization in both cases.

[woodbe]

Thanks, I have undone that particular change.

[woodbe]

The only exception would be if you are collecting latent prints from a dark surface and are using white dusting powder. The assumption with scanner images is the ridges are gray and the valleys are white. When binarizing the scanner image the ridges become black and the valleys stay white. For latents on dark surfaces with white dusting powder, the ridges will be white (light gray) and the valleys black (dark gray) before the binarization step. The evaluator will want to take care to end up with black ridges and white valleys after binarization in both cases.

So the instructions I have created so far assume black powder since we have control over what they are created on. I guess we could provide white powder as an option, but I think we can probably just minimize the expectations to having a light colored background so we don't have to adjust from what we are already expecting.

[woodbe]

The latest addition is to close #90.