In my research i wanna to build an android NDK source code that capture the image with mobile camera, and convert the image to binary data..where Red and blue color was used for detecting change of light. It converted the change of light to binary code by detecting the strength of light, setting it to '1' if exceeding the strength of default color, and to '0' if there is no change. The converted binary was sent to Java code in Android Application.
Like any microcontroller or microprocessor board trainer kits, there are many ARM-Cortex based Android Kits available in the market. You can use such kits to develop your own application and later deploy it on regular mobile handset to test the performance of your app.
Best Luck!
You can take each frame captured by the camera, and find the average light intensity of the image raster matrix.
Basically, you can iterate through all pixels in the raster, and sum up all R, G and B component values from each of those pixels. When you create a sum value (long data type), divide it with 768 times the total number of pixels in the frame. Make sure that the resulting value is a double precision floating point number for best precision.
768 = 256 * 3, where 256 is the maximum value for each colour component - R, G and B and 3 is for each of those 3 colour components.
By doing this, you will get a value from 0 to 1 (double precision floating point value).
When the value is close to 0 the frame was dark, meaning that the light intensity of what the camera is exposed to is mostly dark and if it is close to 1 than the camera is exposed to a very very very bright source of light.
You can put this in an infinite loop and each measurement (acquisition of a value from 0 do 1) can be logged, stored or sent to some service for further processing.
Thank you all,
it's clear now, but i still have problem for saving the frames from mobile camera to a buffer. i need to receive these frames in fixed delay(Periodicity) in 40msec. I've Problem in FPS_range(30000,30000) is returning frames with random delay between 30 or 40 msec ?!!
How can obtain to a fixed delay between frames ..
This particularly depends on the hardware/software configuration.
If you are using, for example, Android as the system of the mobile device whose camera you are utilising, you can attempt to lock the delay between frames by using a specialised (highly customisable) Android system ROM. You might want to root the device and manually turn off all unnecessary processes so that the CPU and other hardware time schedulers can manage to (attempt to) guarantee a steady delay between frames. However, in such complex hw/sw systems such as a mobile phone with an Android OS, this might prove to be more of a challenge than you might think.
Perhaps, using a lower level development board with a camera attached to its available communication port and programming the MCU/MCP directly for that task (taking frames with a fixed delay and storing them into a FIFO-like buffer) might prove much easier than tweeking the mobile device and its OS for that task.
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