.48

BLOOD TRAIL

Hemoglobin band-depth detector. Rear camera, live overlay. Everything runs on the phone, nothing is uploaded.

Add to Home Screen for offline use in the woods.

Tuning

Feature weights

D = green band depth, the real discriminator. Q = red/green ratio. S = blue suppression.

.55
.30
.15
Ranges

Where each feature maps 0 to 1. Widen if nothing lights up, narrow if everything does.

0.25
0.70
1.90
6.0
.05
0.35
Spatial
.60

Erodes the hit map so an isolated noisy pixel cannot light up. Raise it if you get scattered dots on a surface that is obviously not blood.

Blood is small and discrete. Local contrast rejects large uniform areas like red clay banks and rust colored leaf beds.

.35
12
Blood type preset

Different organs bleed differently. Bright is lung, muscle and arterial. Dark is liver, heart and venous. Aged is 6 hours or more, browned out. Wide catches all three and false-alarms more.

Gut shot blood mixed with rumen contents is green brown and this will not find it. No hemoglobin index will.

Rejection

Red floor is the single most important control. The index is a ratio, so in dark areas it explodes on sensor noise and anything faintly warm reads as blood. This is why black cables, shadows and dark trim light up. Raise it until they stop.

.015

Skin veto rejects bright pixels with only a moderate band depth and uncrushed blue. Ordinary skin of any tone already scores low. Lips and fresh scrapes still trigger, because they genuinely are hemoglobin.

Response

If the overlay feels slow to light up, the usual cause is the phone auto white balance pulling red back out over about a second. LOCK freezes it. SNAP removes the fade so hits pop instantly.

.50

Lower is faster. .50 means the detector runs at half resolution, which is plenty for droplets and roughly four times the frame rate.

Camera
1.00 / 1.00 / 1.00

Auto WB estimates the light source from the scene and divides it out. Leave it on. It is the single thing that stops warm indoor light making every brown surface read as blood. Turn it off and use the gray card only when you want fixed numbers for a measurement set.

Display

Readings

No readings yet. Hit PROBE, tap a spot, pick a label.

Diagnostics


  






  
Field protocol

  

    
Goal of the first session is not to find deer. It is to find out whether the index separates blood from your ground cover. Take readings, send them back.

    
Setup

    
    
      
  1. Get real blood. Butcher shop, or the next deer. A cup is plenty.
    2. 
      
  2. Drip it, do not pour it. Single droplets, a spatter, and one smear.
    3. 
      
  3. Put samples on each substrate separately: green grass, dry oak or maple leaves, pine needles, bare dirt, red clay if you have it, gravel, a downed log.
    4. 
      
  4. Before every set of readings, hit the gray card calibration on something neutral.
    5. 
    

    
For each substrate, PROBE and label

    
    
      
  1. One reading on the blood.
    2. 
      
  2. Three readings on the bare substrate right next to it, no blood.
    3. 
      
  3. One reading on the worst lookalike nearby: a red leaf, a berry, rust, orange tape.
    4. 
    

    
Conditions to repeat it in

    
    
Then

    
Open LOG, hit COPY ALL, paste it to me. Grab screenshots too, especially any spot where the overlay lit up on something that was not blood.

    
What the numbers mean