Hello all, my house had a break-in not long ago and I have caught some CCTV footages of the thief. It was at midnight and the CCTV goes into infrared mode so the footage is in black and white. I am in no expert to analyze a CCTV footage so I would like as many help as I can to derive any useful information.
Note These screenshots are from a CCTV video footage and these are the best frame I can get.
Check full size image for face on bottom right.
1. Is there any way to derive certain color information from the photos? i.e colors of clothes or the tone of skin?
2. The thief looks like it is wearing glasses but those are just infrared reflection of the eyes correct?
3. Is there any software I can use to draw the important features of the face and get a sketch out of these?
4. Is there anyway to get the design on the shirt or to see more clearly what shoes or slippers is the thief wearing?
5. Can I use pythagoras theorem or any other formula to get the height of the thief? Or even derive the weight from these footages?
6. Please let me know if any other angle of footage or software that can help me get more information out of my limited CCTV footages before the CCTV got tempered.
Appreciate any help I can get. Thank you.
Hi there,
From the screenshots, it’s a little difficult to assess the original video quality.
To answer your questions…
1. No. The placement of Infra-Red light in a scene enables a suitable camera to visualize objects by their IR properties and not their color. Objects either have a IR reflective or IR absorbent property. Black is absorbed, White is reflected, and then you have all the different shades of grey in between. The IR bulbs on the camera are very low – they have illuminated the wall but not so much the ground area underneath.
2. IR Light again. No detail suggesting glasses.
3. Not quite sure what you mean by ‘draw’. One of the problems with low IR is that it increases the noise and therefore gives poor compression. This is the reason why the images have a blurred effect. You can’t draw around features that have been compressed out.
4. Various digital image processing filters can bring out light and dark features easier. Common image processing software have all these filters. ‘Levels’ being a common one. I use the Retinex Filter in Amped FIVE (Forensic Image & Video Enhancement). It great for balancing uneven illumination and doesn’t increase noise like other filters as much.
5. The math behind single image photogrammetry involves identifying the correlation between 3 axis, x,y and z. Z usually being vertical. Adding in a known height will then give you an estimate of other objects that are also vertical on that same plane. Again, this is possible in Amped FIVE, however the images you have screenshotted would not be entirely suitable. In scenarios like this, many height estimates would be calculated and reported, and then averaged, to account for stance and movement. Even with a completely vertical, not moving subject, the angle of the camera and the distance from object will probably give you a +/- 3cm variation.
6. As stated before, levels adjustment, exposure or other luminance adjustment filters can help – just be careful with noise.
Cropping down to the subject and producing a single image sometime helps in presentation.
Good luck..
Thank you so much for your input Spready, I really appreciated it.
Since you mentioned about IR reflective or IR absorbent, is there a reference of what colors are IR reflective or IR absorbent? I guess it boils down to the pigment of the color on the material correct?
Let's say for example, the "jeans" he is wearing is dark in color. So I assume this means it is IR absorbent. Can be suggest that it is dark in color i.e navy blue or black like jeans or there could be other factors?
I also manage to find a frame and looks like he is wearing shoes and not slippers. Since the IR is not strong enough, I guess it is not possible to see what kind of material the shoe is made off correct?
This is out of the topic but could a external IR Illuminator/IR assist light help in these situation to light up the environment and bring out details in the future? Is it possible for the IR illuminator to be too bring that some important details are lost because it became too bring as it may happen in natural light or is IR a different story?
Thank you!
For colour matching I think you may be able to have a good go your self.
As you have the camera, try different colour clothes in the same location (in the dark) as see how they show up. The results may not be 100% conclusive, but you may, for instance be able to say the tee shirt was not yellow, or red, but possibly blue or black.
In other words, determine which colours could have produced the results you saw, and which colours do not match the results you saw.