openCV cvLoadImage和cvSaveImage中的两个函数接受文件路径作为参数。用于内存缓冲区或文件指针的OpenCV
例如，当保存图像时，它是cvSaveImage（“/ tmp/output.jpg”，dstIpl）并写入磁盘。
有什么办法给这个缓冲区已经在内存中？因此，而不是磁盘写入，输出图像将在内存中。
我也想知道这对于cvSaveImage和cvLoadImage（读取和写入内存缓冲区）。谢谢！
我的目标是将文件的编码（jpeg）版本存储在内存中。和cvLoadImage一样，我想加载一个内存中的jpeg到IplImage格式。
有在libary的SVN版本的一对夫妇的无证功能：
CV_IMPL CvMat* cvEncodeImage(const char* ext,
const CvArr* arr, const int* _params)
CV_IMPL IplImage* cvDecodeImage(const CvMat* _buf, int iscolor)
最新检查指出它们是天然的编码/为BMP，PNG，PPM和TIFF（仅编码解码）。
或者，您可以使用标准图像编码库（例如libjpeg）并操纵IplImage中的数据以匹配编码库的输入结构。
我假设你在linux上工作。从libjpeg.doc：
一个JPEG压缩 操作的粗略轮廓是：
分配 并初始化一个JPEG压缩 对象
指定目的地为 的压缩数据（例如，一个文件）
设置 参数进行压缩，包括 图像尺寸&色彩空间jpeg_start_compress（...）;
而 （扫描线还有待写入）
jpeg_write_scanlines（...）;jpeg_finish_compress（...）;
发布 JPEG压缩对象
做你想要做的就是提供定制的“数据目标（或源）经理”这是在jpeglib.h定义了什么真正的窍门：
struct jpeg_destination_mgr {
JOCTET * next_output_byte; /* => next byte to write in buffer */
size_t free_in_buffer; /* # of byte spaces remaining in buffer */
JMETHOD(void, init_destination, (j_compress_ptr cinfo));
JMETHOD(boolean, empty_output_buffer, (j_compress_ptr cinfo));
JMETHOD(void, term_destination, (j_compress_ptr cinfo));
};
基本上这样设置，所以你的源和/或目标是你想要的内存缓冲区，你应该很好去。
另外，这篇文章可能会好很多，但libjpeg62文档很坦率地说非常好。只需apt-get libjpeg62-dev并阅读libjpeg.doc并查看example.c。如果您遇到问题，无法继续工作，请重新发帖，我确信有人可以提供帮助。
所有你需要从内存缓冲区加载文件是一个不同的src管理器（libjpeg）。我在Ubuntu 8.10中测试了以下代码。
/******************************** First define mem buffer function bodies **************/
<pre>
/*
* memsrc.c
*
* Copyright (C) 1994-1996, Thomas G. Lane.
* This file is part of the Independent JPEG Group's software.
* For conditions of distribution and use, see the accompanying README file.
*
* This file contains decompression data source routines for the case of
* reading JPEG data from a memory buffer that is preloaded with the entire
* JPEG file. This would not seem especially useful at first sight, but
* a number of people have asked for it.
* This is really just a stripped-down version of jdatasrc.c. Comparison
* of this code with jdatasrc.c may be helpful in seeing how to make
* custom source managers for other purposes.
*/
/* this is not a core library module, so it doesn't define JPEG_INTERNALS */
//include "jinclude.h"
include "jpeglib.h"
include "jerror.h"
/* Expanded data source object for memory input */
typedef struct {
struct jpeg_source_mgr pub; /* public fields */
JOCTET eoi_buffer[2]; /* a place to put a dummy EOI */
} my_source_mgr;
typedef my_source_mgr * my_src_ptr;
/*
* Initialize source --- called by jpeg_read_header
* before any data is actually read.
*/
METHODDEF(void)
init_source (j_decompress_ptr cinfo)
{
/* No work, since jpeg_memory_src set up the buffer pointer and count.
* Indeed, if we want to read multiple JPEG images from one buffer,
* this *must* not do anything to the pointer.
*/
}
/*
* Fill the input buffer --- called whenever buffer is emptied.
*
* In this application, this routine should never be called; if it is called,
* the decompressor has overrun the end of the input buffer, implying we
* supplied an incomplete or corrupt JPEG datastream. A simple error exit
* might be the most appropriate response.
*
* But what we choose to do in this code is to supply dummy EOI markers
* in order to force the decompressor to finish processing and supply
* some sort of output image, no matter how corrupted.
*/
METHODDEF(boolean)
fill_input_buffer (j_decompress_ptr cinfo)
{
my_src_ptr src = (my_src_ptr) cinfo->src;
WARNMS(cinfo, JWRN_JPEG_EOF);
/* Create a fake EOI marker */
src->eoi_buffer[0] = (JOCTET) 0xFF;
src->eoi_buffer[1] = (JOCTET) JPEG_EOI;
src->pub.next_input_byte = src->eoi_buffer;
src->pub.bytes_in_buffer = 2;
return TRUE;
}
/*
* Skip data --- used to skip over a potentially large amount of
* uninteresting data (such as an APPn marker).
*
* If we overrun the end of the buffer, we let fill_input_buffer deal with
* it. An extremely large skip could cause some time-wasting here, but
* it really isn't supposed to happen ... and the decompressor will never
* skip more than 64K anyway.
*/
METHODDEF(void)
skip_input_data (j_decompress_ptr cinfo, long num_bytes)
{
my_src_ptr src = (my_src_ptr) cinfo->src;
if (num_bytes > 0) {
while (num_bytes > (long) src->pub.bytes_in_buffer) {
num_bytes -= (long) src->pub.bytes_in_buffer;
(void) fill_input_buffer(cinfo);
/* note we assume that fill_input_buffer will never return FALSE,
* so suspension need not be handled.
*/
}
src->pub.next_input_byte += (size_t) num_bytes;
src->pub.bytes_in_buffer -= (size_t) num_bytes;
}
}
/*
* An additional method that can be provided by data source modules is the
* resync_to_restart method for error recovery in the presence of RST markers.
* For the moment, this source module just uses the default resync method
* provided by the JPEG library. That method assumes that no backtracking
* is possible.
*/
/*
* Terminate source --- called by jpeg_finish_decompress
* after all data has been read. Often a no-op.
*
* NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
* application must deal with any cleanup that should happen even
* for error exit.
*/
METHODDEF(void)
term_source (j_decompress_ptr cinfo)
{
/* no work necessary here */
}
/*
* Prepare for input from a memory buffer.
*/
GLOBAL(void)
jpeg_memory_src (j_decompress_ptr cinfo, const JOCTET * buffer, size_t bufsize)
{
my_src_ptr src;
/* The source object is made permanent so that a series of JPEG images
* can be read from a single buffer by calling jpeg_memory_src
* only before the first one.
* This makes it unsafe to use this manager and a different source
* manager serially with the same JPEG object. Caveat programmer.
*/
if (cinfo->src == NULL) { /* first time for this JPEG object? */
cinfo->src = (struct jpeg_source_mgr *)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
SIZEOF(my_source_mgr));
}
src = (my_src_ptr) cinfo->src;
src->pub.init_source = init_source;
src->pub.fill_input_buffer = fill_input_buffer;
src->pub.skip_input_data = skip_input_data;
src->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */
src->pub.term_source = term_source;
src->pub.next_input_byte = buffer;
src->pub.bytes_in_buffer = bufsize;
}
然后用法很简单。您可能需要用sizeof（）替换SIZEOF（）。找到一个标准的解压缩示例。只需将“jpeg_stdio_src”替换为“jpeg_memory_src”即可。希望有所帮助！
这为我工作
// decode jpg (or other image from a pointer)
// imageBuf contains the jpg image
cv::Mat imgbuf = cv::Mat(480, 640, CV_8U, imageBuf);
cv::Mat imgMat = cv::imdecode(imgbuf, CV_LOAD_IMAGE_COLOR);
// imgMat is the decoded image
// encode image into jpg
cv::vector<uchar> buf;
cv::imencode(".jpg", imgMat, buf, std::vector<int>());
// encoded image is now in buf (a vector)
imageBuf = (unsigned char *) realloc(imageBuf, buf.size());
memcpy(imageBuf, &buf[0], buf.size());
// size of imageBuf is buf.size();
有人问我关于一个C版本，而不是C++：
#include <opencv/cv.h>
#include <opencv/highgui.h>
int
main(int argc, char **argv)
{
char *cvwin = "camimg";
cvNamedWindow(cvwin, CV_WINDOW_AUTOSIZE);
// setup code, initialization, etc ...
[ ... ]
while (1) {
// getImage was my routine for getting a jpeg from a camera
char *img = getImage(fp);
CvMat mat;
// substitute 640/480 with your image width, height
cvInitMatHeader(&mat, 640, 480, CV_8UC3, img, 0);
IplImage *cvImg = cvDecodeImage(&mat, CV_LOAD_IMAGE_COLOR);
cvShowImage(cvwin, cvImg);
cvReleaseImage(&cvImg);
if (27 == cvWaitKey(1)) // exit when user hits 'ESC' key
break;
}
cvDestroyWindow(cvwin);
}
下面是在Delphi中的例子。它转换为一个24位的位图用于OpenCV
function BmpToPIplImageEx(Bmp: TBitmap): pIplImage;
Var
i: Integer;
offset: LongInt;
dataByte: PByteArray;
Begin
Assert(Bmp.PixelFormat = pf24bit, 'PixelFormat must be 24bit');
Result := cvCreateImageHeader(cvSize(Bmp.Width, Bmp.Height), IPL_DEPTH_8U, 3);
cvCreateData(Result);
for i := 0 to Bmp.height - 1 do
Begin
offset := longint(Result.imageData) + Result.WidthStep * i;
dataByte := PByteArray(offset);
CopyMemory(dataByte, Bmp.Scanline[i], Result.WidthStep);
End;
End;
您想将图像写入内存？但是dstIpl已经在记忆中，你希望完成什么？您可以使用dstIpl-> imageData或 - >数据或其他方式访问图像数据。 – mpen 2009-05-07 00:53:56
同样，你可以操纵iplImage的数据缓冲区来加载已经在内存中的图像......只需要使用BGR格式。 – mpen 2009-05-07 00:55:54
我认为原始的海报想编码图像，但保存磁盘读/写。 – M456 2009-05-07 01:05:50