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Added background subtraction example
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‎EXAMPLES/EX_BACKGROUND_SUBTRACTION.hpp

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#include <scamp5.hpp>
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#include "MISC/MISC_FUNCS.hpp"
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using namespace SCAMP5_PE;
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vs_stopwatch frame_timer;
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vs_stopwatch output_timer;
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vs_stopwatch areg_quantization_refresh_timer;
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const areg_t AREG_captured_image = A;
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const areg_t AREG_stored_background = B;
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const areg_t AREG_background_update_mask = C;
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const dreg_t DREG_detected_motion = S0;
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int main()
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{
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vs_init();
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//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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//SETUP IMAGE DISPLAYS
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int disp_size = 2;
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auto display_00 = vs_gui_add_display("Captured Image",0,0,disp_size);
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auto display_01 = vs_gui_add_display("Stored Background",0,disp_size,disp_size);
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auto display_02 = vs_gui_add_display("Background Subtraction Result",0,disp_size*2,disp_size);
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auto display_10 = vs_gui_add_display("Background Update Mask",disp_size,0,disp_size);
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auto display_11 = vs_gui_add_display("Motion",disp_size,disp_size,disp_size);
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//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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//SETUP GUI ELEMENTS & CONTROLLABLE VARIABLES
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int quantization_levels = 16;
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vs_gui_add_slider("quantization_levels",2,32,quantization_levels,&quantization_levels);
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//Each frame the background update mask is steadily increased in value according to the following variables
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//The stored background is updated wherever this mask is high in value
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int bg_mask_increase_value = 10;//value added to mask
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vs_gui_add_slider("bg_mask_inc_value",0,127,bg_mask_increase_value,&bg_mask_increase_value);
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int bg_mask_increase_interval = 250;//time in ms between each addition
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vs_gui_add_slider("bg_mask_inc_interval",0,1000,bg_mask_increase_interval,&bg_mask_increase_interval);
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vs_stopwatch bg_mask_update_timer;
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//Threshold used to detect motion, using frame differencing (i.e. abs(current_frame-previous_frame)
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//The background update mask is reset wherever motion is detected, stopping the background from being updated in those PEs
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int motion_threshold = 16;
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vs_gui_add_slider("motion_threshold",0,127,motion_threshold,&motion_threshold);
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int motion_expansion = 5;
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vs_gui_add_slider("motion_expansion",0,20,motion_expansion,&motion_expansion);
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//The threshold used to detect differences between the stored background and the current frame
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int background_sub_threshold = 32;
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vs_gui_add_slider("background_sub_threshold",0,127,background_sub_threshold,&background_sub_threshold);
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auto gui_btn_store_images = vs_gui_add_button("Set Background");
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vs_on_gui_update(gui_btn_store_images,[&](int32_t new_value)
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{
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scamp5_in(AREG_background_update_mask,127); //Reset Background Mask
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});
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int output_binary_result = 1;
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vs_gui_add_switch("binary_result",output_binary_result == 1,&output_binary_result);
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//Reset background update mask
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scamp5_in(AREG_background_update_mask,127);
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//CONTINOUS FRAME LOOP
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while(true)
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{
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frame_timer.reset();//reset frame_timer
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vs_disable_frame_trigger();
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vs_frame_loop_control();
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//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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//CAPTURE FRAME
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scamp5_kernel_begin();
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mov(E, AREG_captured_image);//store a copy previous frame
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get_image(AREG_captured_image, F); //get new frame
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scamp5_kernel_end();
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//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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//DETECT MOTION BY FRAME DIFFERENCING
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scamp5_in(D,motion_threshold);
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scamp5_kernel_begin();
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//Compute absolute difference between latest frame and previous frame
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sub(F,AREG_captured_image,E);// E = difference between latest and previous frame
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abs(E,F);// F == absolute difference between current and last frame
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//Detect PEs where "motion" occurred due to absolute difference between current and last frame being above threshold
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sub(E,E,D);
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where(E);
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MOV(DREG_detected_motion,FLAG);//Store mask of PEs where there was "motion"
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all();
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scamp5_kernel_end();
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//Expand motion mask to ensure background is not updated in any PEs even near where motion is occuring
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scamp5_kernel_begin();
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SET(RN,RS,RE,RW);
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scamp5_kernel_end();
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for(int n = 0 ; n < motion_expansion; n++)
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{
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scamp5_kernel_begin();
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DNEWS0(S6,DREG_detected_motion);//S6 will contain 1s at locations that S0 will expand into this step
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OR(DREG_detected_motion,S6);//Combine expanded locations with S0 itself
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scamp5_kernel_end();
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}
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//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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//UPDATE BACKGROUND MASK
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//Where motion occurred reset background update mask to minimum value
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scamp5_in(D,-127);
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scamp5_kernel_begin();
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WHERE(DREG_detected_motion);
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mov(AREG_background_update_mask,D);
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all();
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scamp5_kernel_end();
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//If sufficient time has passed, increase the value of mask
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if(bg_mask_update_timer.get_usec() >= bg_mask_increase_interval*1000)
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{
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//Reset Counter
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bg_mask_update_timer.reset();
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//Update Background Update Mask
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scamp5_in(F,bg_mask_increase_value);
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scamp5_kernel_begin();
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add(AREG_background_update_mask,AREG_background_update_mask,F);
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scamp5_kernel_end();
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}
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//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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//UPDATE BACKGROUND, BUT ONLY WHERE BACKGROUND UPDATE MASK IS HIGH VALUE
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int background_update_mask_threshold = 100;
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scamp5_in(F,background_update_mask_threshold);//Threshold at which to perform background update
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scamp5_kernel_begin();
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sub(E,AREG_background_update_mask,F);
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where(E);//Where Background Update Mask > Threshold
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mov(AREG_stored_background,AREG_captured_image);//Update Background
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all();
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scamp5_kernel_end();
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//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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//REFRESH QUANTIZED AREG STORAGE, SNAPS EACH PE'S STORED VALUE TO THE NEAREST QUANTIZED VALUE TO PREVENT VALUE DECAY/DRIFT
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areg_quantization_refresh_timer.reset();
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{
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scamp5_kernel_begin();
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SET(S6);//Use the S6 DREG to track which PEs have been snapped to a quantization level
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scamp5_kernel_end();
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int quantization_interval = 256/(quantization_levels-1);
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int current_value = -127;//Value of the current quantization level
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int decision_value = current_value + quantization_interval/2;//Value to compare with data to determine if it should snap downwards to current quantization level
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//Iterate through each value of quantization, from lowest to highest
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for(int n = 0 ; n < quantization_levels-1 ;n++)
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{
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scamp5_in(F,decision_value);
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scamp5_in(E,current_value);
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scamp5_kernel_begin();
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sub(F,F,AREG_stored_background);
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where(F);//Compare stored data with decision value, FLAG == 1 in PEs with data below the decision value
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AND(S5,S6,FLAG);//Get PEs whose is below the decision value, AND has not been snapped yet, these PEs will be snapped to a value now
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NOT(S6,FLAG);//Update S6, copy the FLAG over now before the next WHERE instruction, all PEs where FLAG = 1 will have had their data snapped to a value
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WHERE(S5);
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mov(AREG_stored_background,E);//Snap the data of these PEs to the current quantization value
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all();
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scamp5_kernel_end();
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//update current and decision values
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current_value += quantization_interval;
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decision_value = current_value + quantization_interval/2;
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}
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//snap all remaining PEs that have not been quantized to the max quantization value
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scamp5_in(E,127);
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scamp5_kernel_begin();
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WHERE(S6);
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mov(AREG_stored_background,E);
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all();
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scamp5_kernel_end();
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}
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int time_spent_on_areg_quantization_refresh = areg_quantization_refresh_timer.get_usec();
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//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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//COMPUTE BACKGROUND SUBTRACTION MASK
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scamp5_in(F,background_sub_threshold);
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scamp5_kernel_begin();
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//Compute absolute difference between background and current frame
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sub(D,AREG_captured_image,AREG_stored_background);
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abs(E,D);
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//Find where absolute difference is above threshold, and copy the current frames data into these PEs
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sub(E,E,F);
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where(E);
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MOV(S5,FLAG);//Store binary background subtraction mask/result
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all();
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scamp5_kernel_end();
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//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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//OUTPUT IMAGES
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output_timer.reset();
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//display current captured frame and thresholded image
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output_4bit_image_via_DNEWS(AREG_captured_image,display_00);
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output_4bit_image_via_DNEWS(AREG_stored_background,display_01);
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output_4bit_image_via_DNEWS(AREG_background_update_mask,display_10);
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scamp5_output_image(DREG_detected_motion,display_11);
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if(output_binary_result)
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{
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scamp5_output_image(S5,display_02);
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}
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else
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{
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//Generate analogue background subtraction image using the binary background subtraction mask
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scamp5_in(E,-127);
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scamp5_kernel_begin();
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WHERE(S5);
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mov(E,AREG_captured_image);
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ALL();
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scamp5_kernel_end();
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output_4bit_image_via_DNEWS(E,display_02);
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}
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int output_time_microseconds = output_timer.get_usec();//get the time taken for image output
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//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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//OUTPUT TEXT INFO
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int frame_time_microseconds = frame_timer.get_usec(); //get the time taken this frame
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int max_possible_frame_rate = 1000000/frame_time_microseconds; //calculate the possible max FPS
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int image_output_time_percentage = (output_time_microseconds*100)/frame_time_microseconds; //calculate the % of frame time which is used for image output
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vs_post_text("time_spent_on_areg_quantization_refresh %d\n",time_spent_on_areg_quantization_refresh);
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vs_post_text("frame time %d microseconds(%%%d image output), potential FPS ~%d \n",frame_time_microseconds,image_output_time_percentage,max_possible_frame_rate); //display this values on host
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}
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return 0;
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}
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‎scamp5_main.cpp

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//#include "EXAMPLES/EX04_IMAGE_THRESHOLDING.hpp"
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//#include "EXAMPLES/EX05_AREG_NEWS.hpp"
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//#include "EXAMPLES/EX06_SIMPLE_EDGE_DETECTION.hpp"
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#include "EXAMPLES/EX07_DNEWS.hpp"
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//#include "EXAMPLES/EX07_DNEWS.hpp"
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//#include "EXAMPLES/EX08_DREG_SHIFTING.hpp"
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//#include "EXAMPLES/EX09_DREG_EXPAND_AND_ERODE.hpp"
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//#include "EXAMPLES/EX10_HALF_SCALING.hpp"
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#include "EXAMPLES/EX_BACKGROUND_SUBTRACTION.hpp"

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