WSQ image dimensions

[Edza]

Hi,

Noticed this comment:
// :TODO: should be determined automatically from WSQ image
const getHorizontalScanningLine = (): string => '500';
// :TODO: should be determined automatically from WSQ image
const getVerticalScanningLine = (): string => '750';

What way would you recommend to implement this?

[ivosh]

I have a solution for this somewhere. Let me dig it out in the next couple of days.
Feel free to ping if there is no response in 2 weeks.

[Edza]

Great! Thanks

[Edza]

Looks like .wsq files have dimensions encoded in them:

PIX_WIDTH 320
PIX_HEIGHT 480
PIX_DEPTH 8
PPI 500
LOSSY 1
COLORSPACE GRAY
COMPRESSION WSQ

Maybe a simple extraction would be with regex?

[ivosh]

I have pushed the initial image header detection stuff in version 0.5.0 (4fd18c9).

I still need to work on integrating this into NistEncodeOptions and examples.

[Edza]

I tried to search for the WSQ spec and did not find if PIX_WIDTH and HEIGHT are mandatory in WSQ files. There was a mention of a WSQ meta file... is there any specification that you are using?

[ivosh]

WSQ specification goes under the following name WSQ GRAY-SCALE FINGERPRINT IMAGE COMPRESSION SPECIFICATION. Googling it up leads for example here: https://www.fbibiospecs.cjis.gov/Document/Get?fileName=WSQ_Gray-scale_Specification_Version_3_1_Final.pdf

However PIX_WIDTH and others you were referring to form a part of specially formatted comment block called NISTCOM. I don't have any authoritative source for it, but have a look for example here: https://nvlpubs.nist.gov/nistpubs/Legacy/IR/nistir6813.pdf

[Edza]

Could you please share the width/height calculating code?

[ivosh]

The code is already here: https://github.com/ivosh/node-nist/blob/master/src/imageHeader.ts

Unfortunately I did not have time to update tests, examples and README to use it.