测试硬件pcduino(arm)，操作系统ubuntu 3.4.29+ armv7l GNU/Linux。测试文件，图片jpeg,大约1.3M。测试内容统计图片的RGB里的值，存在数据库里将来看看能不能做搜索用。
先是用python，开发速度非常快，但是效率有点问题，所以有用C做了一下。以下是代码和两次的测试结果。C使用的jpeglib库8.0版本。
python代码
#!/bin/python
#-*- coding:utf-8 -*-
# Filename:
# Revision: 1.0
# Date: 2013-12-04
# Author: simonzhang
# web: www.simonzhang.net
# Email: simon-zzm@163.com
### END INIT INFO
from PIL import Image
# 对RGB简历字典
R = {}
G = {}
B = {}
# 初始化值
for i in xrange(256):
R[i] = 0
G[i] = 0
B[i] = 0
# 大图片需要处理很长时间，所以要用python可以按比例将图缩小
a = Image.open('123.jpg')
#a = a.resize((int(a.size[0] * 0.1), int(a.size[1] * 0.1)), Image.ANTIALIAS)
x = a.size[0]
y = a.size[1]
# 循环处理每个像素点的RGB值
for lx in xrange(x):
for ly in xrange(y):
rgb = a.getpixel((lx, ly))
R[rgb[0]] += 1
G[rgb[1]] += 1
B[rgb[2]] += 1
# 打印最终结果
print sorted(R.items(), key=lambda R:R[1],reverse=True)[0]
print sorted(G.items(), key=lambda G:G[1],reverse=True)[0]
print sorted(B.items(), key=lambda B:B[1],reverse=True)[0]
C代码
/*
*Filename:
* Revision: 1.0
* Date: 2013-12-04
* Author: simonzhang
* web: www.simonzhang.net
* Email: simon-zzm@163.com
*/
#include
#include
#include
/* we will be using this uninitialized pointer later to store raw, uncompressd image */
//unsigned char *raw_image = NULL;
/* */
int max_num;
/* find max values*/
int sort_values(int arr[255])
{
int largest1, largest2, temp;
max_num = 0;
largest1 = arr[0];
largest2 = arr[1];
if (largest1 < largest2)
{
temp = largest1;
largest1 = largest2;
largest2 = temp;
}
int i;
for (i = 2; i < 255; i++)
{
if (arr[i] >= largest1)
{
largest2 = largest1;
largest1 = arr[i];
max_num = i;
}
else if (arr[i] > largest2)
{
largest2 = arr[i];
}
}
return largest1;
}
read_jpeg_file(char *filename)
{
/* these are standard libjpeg structures for reading(decompression) */
struct jpeg_decompress_struct cinfo;
struct jpeg_error_mgr jerr;
/* libjpeg data structure for storing one row, that is, scanline of an image */
JSAMPROW row_pointer[1];
FILE *infile = fopen( filename, "rb" );
unsigned long location = 0;
int i = 0;
if ( !infile )
{
printf("Error opening jpeg file %s\n!", filename );
return -1;
}
/* here we set up the standard libjpeg error handler */
cinfo.err = jpeg_std_error( &jerr );
/* setup decompression process and source, then read JPEG header */
jpeg_create_decompress( &cinfo );
/* this makes the library read from infile */
jpeg_stdio_src( &cinfo, infile );
/* reading the image header which contains image information */
jpeg_read_header( &cinfo, TRUE );
/* Uncomment the following to output image information, if needed. */
/* Start decompression jpeg here */
jpeg_start_decompress( &cinfo );
/* allocate memory to hold the uncompressed image */
//raw_image = (unsigned char*)malloc( cinfo.output_width*cinfo.output_height*cinfo.num_components );
/* now actually read the jpeg into the raw buffer */
row_pointer[0] = (unsigned char *)malloc( cinfo.output_width*cinfo.num_components );
/* read one scan line at a time */
int r[255], g[255], b[255];
for(i=0;i<255;i++)
{
r[i] = 0;
g[i] = 0;
b[i] = 0;
}
while( cinfo.output_scanline < cinfo.image_height )
{
jpeg_read_scanlines( &cinfo, row_pointer, 1 );
for( i=0; i
先是测试python部分
#time python countrgb.py
(12, 510858)
(17, 429677)
(9, 662996)
real 11m4.009s
user 10m42.200s
sys 0m1.090s
开始测试C的部分
首先优化编译一下
#gcc countrgb.c -l jpeg -O3 -o countrgb
#time ./countrgb 123.jpg
12,510858
17,429677
9,662996
real 0m0.750s
user 0m0.730s
sys 0m0.010s
两次统计结果相同，说明统计方法没有问题。python用了11分钟，C用了0.75秒，看来真的不是一般的快了。C代码编译后的文件8K，静态编译500多K。不过我是喜欢用python，开发速度快，结构清晰。
