Skip to content

Instantly share code, notes, and snippets.

Created May 7, 2018
What would you like to do?
SOD CNN multi-class object detection intro using the Tiny VOC (20 classes) model -
* Programming introduction with the SOD Embedded Convolutional/Recurrent Neural Networks (CNN/RNN) API.
* Copyright (C) PixLab | Symisc Systems,
* Compile this file together with the SOD embedded source code to generate
* the executable. For example:
* gcc sod.c cnn_voc.c -lm -Ofast -march=native -Wall -std=c99 -o sod_cnn_intro
* Under Microsoft Visual Studio (>= 2015), just drop `sod.c` and its accompanying
* header files on your source tree and you're done. If you have any trouble
* integrating SOD in your project, please submit a support request at:
* This simple program is a quick introduction on how to embed and start
* experimenting with SOD without having to do a lot of tedious
* reading and configuration.
* Make sure you have the latest release of SOD from:
* The SOD Embedded C/C++ documentation is available at:
#include <stdio.h>
#include "sod.h"
int main(int argc, char *argv[])
/* Input image (pass a path or use the test image shipped with the samples ZIP archive) */
const char *zInput = argc > 1 ? argv[1] : "./test.png";
/* Draw detection boxes (i.e. rectangles) on this output image which
* is a copy of the input plus the boxes.
const char *zOut = argc > 2 ? argv[2] : "./out.png";
* The CNN handle that should perform the detection process */
sod_cnn *pNet;
/* Load the input image */
sod_img imgIn = sod_img_load_from_file(zInput,SOD_IMG_COLOR/* Full colors*/);
if ( == 0) {
/* Invalid path, unsupported format, memory failure, etc. */
puts("Cannot load input image..exiting");
return 0;
/* Make a copy so we can draw anything we want. */
sod_img imgOut = sod_copy_image(imgIn);
int rc;
const char *zErr; /* Error log if any */
* Create our CNN handle using the built-in fast
* architecture trained on the Pascal VOC dataset
* and is able to detect 20 classes of objects at
* real-time on a modern CPU.
rc = sod_cnn_create(&pNet, ":voc", "./tiny20.sod", &zErr);
* ":voc" is the magic word for the built-in Pascal VOC (20 classes)
* fast architecture. The list of built-in Magic words (pre-ready to use
* configurations and their associated models) are documented here:
* "tiny20.sod" is the pre-trained model associated with the ":fast" architecture
* and is available to download from
if (rc != SOD_OK) {
/* Display the error message and exit */
return 0;
* A sod_box instance always store the coordinates for each detected object
* returned by the CNN via sod_cnn_predict() as we'll see later.
sod_box *box;
int i, nbox;
/* Prepare our input image for the detection process which
* is resized to the network dimension (This op is always very fast)
float * blob = sod_cnn_prepare_image(pNet, imgIn);
if (!blob) {
/* Very unlikely this happen: Invalid architecture, out-of-memory */
puts("Something went wrong while preparing image..");
return 0;
puts("Starting CNN object detection");
/* Detect.. */
sod_cnn_predict(pNet, blob, &box, &nbox);
/* Report the detection result. */
printf("%d object(s) were detected..\n",nbox);
for (i = 0; i < nbox; i++) {
/* Report the coordinates, name and score of the current detected object */
printf("(%s) X:%d Y:%d Width:%d Height:%d score:%f%%\n", box[i].zName, box[i].x, box[i].y, box[i].w, box[i].h, box[i].score * 100);
if( box[i].score < 0.3) continue; /* Discard low score detection, remove if you want to report all objects */
* Draw a rose (RGB: 255,0,255) rectangle of width 3 on the object coordinates. */
sod_image_draw_bbox_width(imgOut, box[i], 3, 255., 0, 225.);
/* Of course, one could draw a circle via sod_image_draw_circle() or
* crop the entire region via sod_crop_image() instead of drawing a rectangle. */
/* Finally save our output image with the boxes drawn on it */
sod_img_save_as_png(imgOut, zOut);
/* Cleanup */
/* Release all resources allocated to the CNN handle */
return 0;
Copy link

symisc commented May 7, 2018

SOD Embedded Homepage:
SOD C/C++ API documentation:
Getting Started with SOD Embedded:

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment