If everything else was equal a 640x480 would have twice the resolution clarity of a 320x240. Someone might be able to explain this a lot better but it's the number of pixels, 640 along the X axis, and 480 along the Y axis. Previously I had thought 640x480 was 4x better than 330x240 bc if u add the total of each its 4x more. But IR Defense explained that that's not how it works. It's that 640 is two times 320 and 480 is two times 240 x axis by x axis and y axis by y axis.
Then there's the core and it's microns. The LOWER the number of microns, the MORE amt information can fit on each pixel, the better.
Then there's the display screen quality OLED vs LCD (OLED is better). The display screen also has a pixel count, which is also different from resolution(800x600 vs 640x480 usually... this is not generally what people refer to when talking about 640 vs 320 or 336 or 384)
Then there's a bunch of stuff I can't explain. Someone might correct me on the above but I think that's accurate...ish
Yes 2x is right, a 640 using 2x zoom is the same as a 320 unit with the same lens mm.
Pixels are on the LCD or OLED screen
detectors are on the microbolometer sensor
A b/w (8 bit) pixel can only be made to change from black thru 254 brightness levels(shades of grey) to white.
A b/w (10bit) pixel can only be made to change from black thru 1022 brightness levels(shades of grey) to white.
So there is no changing amount of data placed within a pixel, a pixel is a single unit that can only have its brightness level adjusted.
Having a 800x600 display will have to have a 640x480 detector re-sampled to up-convert the lower quality detector to fit the higher quality screen. A decision will have to be made in firmware as to how the sensors arrays 640 detectors will be resampled to the displays 800 pixels. The microbolometers individual detector can also only contain 8 bit or 10 bit information. The display will have to multiply 1.25 by the number of detectors to have the 640 fit into 800, but since you can't have 1.25 of a pixel it has to be resampled.
detector pitch is measured in microns, a smaller number = more detectors per inch but that does not matter cuz they are not sold by the inch but sold by the array size IE 320x240 or 640x480 etc etc
Smaller core = smaller lenses this saves the company money as germanium is $$$$$
640 core = 75% more detectors over a 320 core, but also has a 75% larger FOV (if using the same mm lens) so resolution has not changed. 75% more detectors and 75% more FOV resolving power has not changed.
The ratio of detectors to FOV is the same.
The detail is sharper on the display because you squeezed the larger FOV with more detectors that go with it on to the same LCD or OLED screen, so dots per inch of information goes up.
But the rabbit got smaller vs a 336 core with same lens, so did everything else didn't it?
Now the trees and critters are 1/2 the size but everything looks sharper.
This detail improvement is based on as you make things smaller the image gets sharper or more dots per inch.
Place a quarter at 100yds and view it with a 336 75mm core, then view it with a 75mm 640 core.
640 core will not see it unless you zoom in at 2x, which is the same as a 336 core at 1x.
Resolving power is based on the detector pitch and the lens mm, the size of the detector has nothing to do with resolving power only how much the FOV. Larger detector larger FOV with the same lens.
Lets use say a 20 degree FOV using a 640 detector, the detector will see the 20 degrees of image which will be stretched across the 640 detectors on the sensor. Notice how the pitch does not matter, only the FOV and number of detectors.
Now if you had a 50 micron pitch detector you would need a lens double the size compared to a 25 micron detector, or 4x larger then a 12 micron detector would need.
The micron size has nothing to do with the clarity, but has everything to do with the size of the detector and the size of the lens . The sensitivity of the detector, the amount of LWIR that passes thru the lens material, the quality of the display screen, as well as the firmware that cleans up the information that is detected are what makes one unit stand out over another.
A lot of magic happens to make these awesome images the thermal units we have available to us today happen.
All the thermal MFG's have stepped up the game and the images the units produce show it.
Hopefully prices will continue to drop.