i tried to convert a dicom image read from a gdcm image reader which has photometric interpretation as 'monochrome2' and pixel format as unsigned int 16 or uint16, i tried the following code over it, but is not giving the required image, please help.
QVector<QRgb> table(2);
for(int c=0;c<256;c++)
{
table.append(qRgb(c,c,c));
}
std::cout << "this is the format UINT16" << std::endl;
int size = dimX*dimY*2; // length of data in buffer, in bytes
quint8 * output = reinterpret_cast<quint8*>(buffer);
const quint16 * input = reinterpret_cast<const quint16*>(buffer);
do {
*output++ = (*input) >> 8;
} while (size -= 2);
imageQt = new QImage(output, dimX, dimY, QImage::Format_Indexed8);
imageQt->setColorTable(table);
regards
I think I see your problem. You are writing the data to output and incrementing the pointer to output as you go along.
You then create the QImage pointing to the end of the bitmap.
You need to do the following:
imageQt = new QImage( reinterpret_cast< uchar* >( buffer ), dimX, dimY, QImage::Format_Indexed8);
Edit: Also you don't advance the input pointer.
You need to change your inner loop to the following:
*output++ = (*input++) >> 8;
Related
I'm trying to get started with the VP8 library, I'm not building it in the standard way they tell you to, I just loaded all of the main files and the "encoder" folder into a new Visual Studio C++ DLL project, and just included the C files in an extern "C" dll export function, which so far builds fine etc., I just have no idea where to start with the C++ API to encode, say, 3 frames of ARGB data into a very basic video, just to get started
The only example I could find is in the examples folder called simple_encoder.c, although their premise is that they are loading in another file already and parsing its frames then converting it, so it seems a bit complicated, I just want to be able to pass in a byte array of a few ARGB frames and have it output a very simple VP8 video
I've seen How to encode series of images into VP8 using WebM VP8 Encoder API? (C/C++) but the accepted answer just links to the build instructions and references the general specification of the vp8 format, the closest I could find there is the example encoding parameters but I just want to do everything from C++ and I can't seem to find any other examples, besides for the default one simple_encoder.c?
Just to cite some of the relevant parts I think I understand, but still need more help on
//in int main...
...
vpx_image_t raw;
if (!vpx_img_alloc(&raw, VPX_IMG_FMT_I420, info.frame_width,
info.frame_height, 1)) {
//"Failed to allocate image." error
}
So that part I think I understand for the most part, VPX_IMG_FMT_I420 is the only part that's not made in this file itself, but its in vpx_image.h, first as
#define VPX_IMG_FMT_PLANAR
//then after...
typedef enum vpx_img_fmt {
VPX_IMG_FMT_NONE,
VPX_IMG_FMT_RGB24, /**< 24 bit per pixel packed RGB */
///some other formats....
VPX_IMG_FMT_ARGB, /**< 32 bit packed ARGB, alpha=255 */
VPX_IMG_FMT_YV12 = VPX_IMG_FMT_PLANAR | VPX_IMG_FMT_UV_FLIP | 1, /**< planar YVU */
VPX_IMG_FMT_I420 = VPX_IMG_FMT_PLANAR | 2,
} vpx_img_fmt_t; /**< alias for enum vpx_img_fmt */
So I guess part of my question is answered already just from writing this, that one of the formats is VPX_IMG_FMT_ARGB, although I don't where where it's defined, but I'm guessing in the above code I would replace it with
const VpxInterface *encoder = get_vpx_encoder_by_name("v8");
vpx_image_t raw;
VpxVideoInfo info = { 0, 0, 0, { 0, 0 } };
info.frame_width = 1920;
info.frame_height = 1080;
info.codec_fourcc = encoder->fourcc;
info.time_base.numerator = 1;
info.time_base.denominator = 24;
bool didIt = vpx_img_alloc(&raw, VPX_IMG_FMT_ARGB,
info.frame_width, info.frame_height/*example width and height*/, 1)
//check didIt..
vpx_codec_enc_cfg_t cfg;
vpx_codec_ctx_t codec;
vpx_codec_err_t res;
res = vpx_codec_enc_config_default(encoder->codec_interface(), &cfg, 0);
//check if !res for error
cfg.g_w = info.frame_width;
cfg.g_h = info.frame_height;
cfg.g_timebase.num = info.time_base.numerator;
cfg.g_timebase.den = info.time_base.denominator;
cfg.rc_target_bitrate = 200;
VpxVideoWriter *writer = NULL;
writer = vpx_video_writer_open(outfile_arg, kContainerIVF, &info);
//check if !writer for error
bool startIt = vpx_codec_enc_init(&codec, encoder->codec_interface(), &cfg, 0);
//not even sure where codec was set actually..
//check !startIt for error starting
//now the next part in the original is where it reads from the input file, but instead
//I need to pass in an array of some ARGB byte arrays..
//thing is, in the next step they use a while loop for
//vpx_img_read(&raw, fopen("path/to/YV12formatVideo", "rb"))
//to set the contents of the raw vpx image allocated earlier, then
//they call another program that writes it to the writer object,
//but I don't know how to read the actual ARGB data directly into the raw image
//without using fopen, so that's one question (review at end)
//so I'll just put a placeholder here for the **question**
//assuming I have an array of byte arrays stored individually
//for simplicity sake
int size = 1920 * 1080 * 4;
uint8_t imgOne[size] = {/*some big byte array*/};
uint8_t imgTwo[size] = {/*some big byte array*/};
uint8_t imgThree[size] = {/*some big byte array*/};
uint8_t *images[] = {imgOne, imgTwo, imgThree};
int framesDone = 0;
int maxFrames = 3;
//so now I can replace the while loop with a filler function
//until I find out how to set the raw image with ARGB data
while(framesDone < maxFrames) {
magicalFunctionToSetARGBOfRawImage(&raw, images[framesDone]);
encode_frame(&codec, &raw, framesDone, 0, writer);
framesDone++;
}
//now apparently it needs to be flushed after
while(encode_frame(&codec, 0, -1, 0, writer)){}
vpx_img_free(&raw);
bool isDestroyed = vpx_codec_destroy(&codec);
//check if !isDestroyed for error
//now we gotta define the encode_Frames function, but simpler
//(and make it above other function for reference purposes
//or in header
static int encode_frame(
vpx_codex_ctx_t *coydek,
vpx_image_t pic,
int currentFrame,
int flags,
VpxVideoWriter *koysayv/*writer*/
) {
//now to substitute their encodeFrame function for
//the actual raw calls to simplify things
const DidIt = vpx_codec_encode(
coydek,
pic,
currentFrame,
1,//duration I think
flags,//whatever that is
VPX_DL_REALTIME//different than simlpe_encoder
);
if(!DidIt) return;//error here
vpx_codec_iter_t iter = 0;
const vpx_codec_cx_pkt_t *pkt = 0;
int gotThings = 0;
while(
(pkt = vpx_codec_get_cx_data(
coydek,
&iter
)) != 0
) {
gotThings = 1;
if(
pkt->kind
== VPX_CODEC_CX_FRAME_PKT //don't exactly
//understand this part
) {
const
int
keyframe = (
pkt
->
data
.frame
.flags
&
VPX_FRAME_IS_KEY
) != 0; //don'texactly understand the
//& operator here or how it gets the keyframe
bool wroteFrame = vpx_video_writer_write_frame(
koysayv,
pkt->data.frame.buf
//I'm guessing this is the encoded
//frame data
,
pkt->data.frame.sz,
pkt->data.frame.pts
);
if(!wroteFrame) return; //error
}
}
return gotThings;
}
Thing is though, I don't know how to actually read the
ARGB data into the RAW image buffer itself, as mentioned
above, in the original example, they use
vpx_img_read(&raw, fopen("path/to/file", "rb"))
but if I'm starting off with the byte arrays themselves
then what function do I use for that instead of the file?
I have a feeling it can be solved by the source code for the vpx_img_read found in tools_common.c function:
int vpx_img_read(vpx_image_t *img, FILE *file) {
int plane;
for (plane = 0; plane < 3; ++plane) {
unsigned char *buf = img->planes[plane];
const int stride = img->stride[plane];
const int w = vpx_img_plane_width(img, plane) *
((img->fmt & VPX_IMG_FMT_HIGHBITDEPTH) ? 2 : 1);
const int h = vpx_img_plane_height(img, plane);
int y;
for (y = 0; y < h; ++y) {
if (fread(buf, 1, w, file) != (size_t)w) return 0;
buf += stride;
}
}
return 1;
}
although I personally am not experienced enough to necessarily know how to get a single frames ARGB data in, I think the key part is fread(buf, 1, w, file) which seems to read parts of file into buf which represents img->planes[plane];, which I think then by reading into buf that automatically reads into img->planes[plane];, but I'm not sure if that is the case, and also not sure how to replace the fread from file to just take in a bye array that is alreasy loaded into memory...
VPX_IMG_FMT_ARGB is not defined because not supported by libvpx (as far as I have seen). To compress an image using this library, you must first convert it to one of the supported format, like I420 (VPX_IMG_FMT_I420). The code here (not mine) : https://gist.github.com/racerxdl/8164330 do it well for the RGB format. If you don't want to use libswscale to make the conversion from RGB to I420, you can do things like this (this code convert a RGBA array of bytes to a I420 vpx_image that can be use by libvpx):
unsigned int tx = <width of your image>
unsigned int ty = <height of your image>
unsigned char *image = <array of bytes : RGBARGBA... of size ty*tx*4>
vpx_image_t *imageVpx = <result that must have been properly initialized by libvpx>
imageVpx->stride[VPX_PLANE_U ] = tx/2;
imageVpx->stride[VPX_PLANE_V ] = tx/2;
imageVpx->stride[VPX_PLANE_Y ] = tx;
imageVpx->stride[VPX_PLANE_ALPHA] = tx;
imageVpx->planes[VPX_PLANE_U ] = new unsigned char[ty*tx/4];
imageVpx->planes[VPX_PLANE_V ] = new unsigned char[ty*tx/4];
imageVpx->planes[VPX_PLANE_Y ] = new unsigned char[ty*tx ];
imageVpx->planes[VPX_PLANE_ALPHA] = new unsigned char[ty*tx ];
unsigned char *planeY = imageVpx->planes[VPX_PLANE_Y ];
unsigned char *planeU = imageVpx->planes[VPX_PLANE_U ];
unsigned char *planeV = imageVpx->planes[VPX_PLANE_V ];
unsigned char *planeA = imageVpx->planes[VPX_PLANE_ALPHA];
for (unsigned int y=0; y<ty; y++)
{
if (!(y % 2))
{
for (unsigned int x=0; x<tx; x+=2)
{
int r = *image++;
int g = *image++;
int b = *image++;
int a = *image++;
*planeY++ = max(0, min(255, (( 66*r + 129*g + 25*b) >> 8) + 16));
*planeU++ = max(0, min(255, ((-38*r + -74*g + 112*b) >> 8) + 128));
*planeV++ = max(0, min(255, ((112*r + -94*g + -18*b) >> 8) + 128));
*planeA++ = a;
r = *image++;
g = *image++;
b = *image++;
a = *image++;
*planeA++ = a;
*planeY++ = max(0, min(255, ((66*r + 129*g + 25*b) >> 8) + 16));
}
}
else
{
for (unsigned int x=0; x<tx; x++)
{
int const r = *image++;
int const g = *image++;
int const b = *image++;
int const a = *image++;
*planeA++ = a;
*planeY++ = max(0, min(255, ((66*r + 129*g + 25*b) >> 8) + 16));
}
}
}
I am using openimageIO to read and display an image from a JPG file, and I now need to store the RGB values in arrays so that I can manipulate and re-display them later.
I want to do something like this:
for (int i=0; i<picturesize;i++)
{
Rarray[i]=pixelredvalue;
Garray[i]=pixelgreenvalue;
Barray[i]=pixelbluevalue;
}
This is an openimageIO source that I found online: https://people.cs.clemson.edu/~dhouse/courses/404/papers/openimageio.pdf
"Section 3.2: Advanced Image Output" (pg 35) is the closest to what I'm doing, but I don't understand how I can use the channels to write pixel data to arrays. I also don't fully understand the difference between "writing" and "storing in an array". This is the piece of code in the reference that I am talking about:
int channels = 4;
ImageSpec spec (width, length, channels, TypeDesc::UINT8);
spec.channelnames.clear ();
spec.channelnames.push_back ("R");
spec.channelnames.push_back ("G");
spec.channelnames.push_back ("B");
spec.channelnames.push_back ("A");
I managed to read the image and display it using the code in the reference, but now I need to store all the pixel values in my array.
Here is another useful piece of code from the link, but again, I can't understand how to retrieve the individual RGB values and place them into an array:
#include <OpenImageIO/imageio.h>
OIIO_NAMESPACE_USING
...
const char *filename = "foo.jpg";
const int xres = 640, yres = 480;
const int channels = 3; // RGB
unsigned char pixels[xres*yres*channels];
ImageOutput *out = ImageOutput::create (filename);
if (! out)
return;
ImageSpec spec (xres, yres, channels, TypeDesc::UINT8);
out->open (filename, spec);
out->write_image (TypeDesc::UINT8, pixels);
out->close ();
ImageOutput::destroy (out);
But this is about writing to a file, and still does not solve my problem. This is on page 35.
Let's assume, that your code which reads an image, looks like this (snippet from OpenImageIO 1.7 Programmer Documentation, Chapter 4.1 Image Input Made Simple, page 55):
ImageInput *in = ImageInput::open (filename);
const ImageSpec &spec = in->spec();
int xres = spec.width;
int yres = spec.height;
int channels = spec.nchannels;
std::vector<unsigned char> pixels (xres*yres*channels);
in->read_image (TypeDesc::UINT8, &pixels[0]);
in->close();
ImageInput::destroy (in);
Now all the bytes of the image are contained in std::vector<unsigned char> pixels.
If you want to access the RGB valuse of the pixel at positon x, y, the you can do it like this:
int pixel_addr = (y * yres + x) * channels;
unsigned char red = pixels[pixel_addr];
unsigned char green = pixels[pixel_addr + 1];
unsigned char blue = pixels[pixel_addr + 2];
Since all the pixels are stored in pixels, there is no reason to store them in separate arrays for the 3 color channels.
But if you want to store the red, green and blue values in separated arrays, then you can do it like this:
std::vector<unsigned char> Rarray(x_res*yres);
std::vector<unsigned char> Garray(x_res*yres);
std::vector<unsigned char> Barray(x_res*yres);
for (int i=0; i<x_res*yres; i++)
{
Rarray[i] = pixels[i*channels];
Garray[i] = pixels[i*channels + 1];
Barray[i] = pixels[i*channels + 2];
}
Of course the pixels have to be tightly packed to pixels (line alignment of 1).
I'm struggling at the moment and hope that someone can help me.
I have to get an Image out of a SQL database (like with SQLGetData) and than convert that data to a CImage so I can view it in my program.
Thanks for any help!
SQLGetData(m_Hstmt, col, SQL_C_BINARY, BinaryPtr, 0, &cbData)
The problem can be reduced to loading a CImage from a byte array, since that is what you get from SQLGetData.
You did not indicate whether you mean to use ATL or MFC, but in both cases it is a little bit awkward as there is no such thing as a public ::LoadFromBuffer function.
This answer should do:
https://stackoverflow.com/a/6759701/1132334
It explains how to create a bitmap structure from a byte buffer and construct a CImage from there.
It is going to be tricky if you need to handle different picture formats. In this case, write the raw bytes to a memory mapped file and then use the CImage::Load(IStream*) overload.
EDIT: its all been done before... https://stackoverflow.com/a/14035492/1132334 and https://stackoverflow.com/a/38710933/1132334
Thanks for all the replies so far. Acoording to #dlatikay answer, this is my code so far. But I'm not sure about the types and somehow my Image stayes black (when I save it to file system)
heres my code so far.
SQLLEN cbData;
CImage image;
BYTE* imgBits;
m_Rc = SQLGetData(m_Hstmt, 1, SQL_C_BINARY, imgBits, 0, &cbData);
if (SQL_SUCCEEDED(m_Rc))
{
width = 317;
height = 159;
BITMAPINFOHEADER bmInfohdr;
// Create the header info
bmInfohdr.biSize = sizeof(BITMAPINFOHEADER);
bmInfohdr.biWidth = width;
bmInfohdr.biHeight = -height;
bmInfohdr.biPlanes = 1;
bmInfohdr.biBitCount = 8 * 8;
bmInfohdr.biCompression = BI_RGB;
bmInfohdr.biSizeImage = width*height * 8;
bmInfohdr.biXPelsPerMeter = 0;
bmInfohdr.biYPelsPerMeter = 0;
bmInfohdr.biClrUsed = 0;
bmInfohdr.biClrImportant = 0;
BITMAPINFO bmInfo;
bmInfo.bmiHeader = bmInfohdr;
bmInfo.bmiColors[0].rgbBlue = 255;
// Allocate some memory and some pointers
unsigned char * p24Img = new unsigned char[width*height * 3];
BYTE *pTemp, *ptr;
pTemp = (BYTE*)imgBits;
ptr = p24Img;
// Convert image from RGB to BGR
for (DWORD index = 0; index < width*height; index++)
{
unsigned char r = *(pTemp++);
unsigned char g = *(pTemp++);
unsigned char b = *(pTemp++);
*(ptr++) = b;
*(ptr++) = g;
*(ptr++) = r;
}
// Create the CImage
image.Create(width, height, 8, NULL);
image.Save(_T("c:\\temp\\image1.bmp")); // for testing
}
I'm using the Leptonica Library to process some pictures. After that I want to show them in my QT GUI. Leptonica is using their own format Pix for the images, while QT is using their own format QPixmap. At the moment the only way for me is to save the pictures after processing as a file ( like bmp ) and then load them again with a QT function call. Now I want to convert them in my code, so I dont need to take the detour with saving them on the filesystem. Any ideas how to do this?
Best Regards
// edit:
Okay as already suggested I tried to convert the PIX* to a QImage.
The PIX* is defined like this:
http://tpgit.github.com/Leptonica/pix_8h_source.html
struct Pix
{
l_uint32 w; /* width in pixels */
l_uint32 h; /* height in pixels */
l_uint32 d; /* depth in bits */
l_uint32 wpl; /* 32-bit words/line */
l_uint32 refcount; /* reference count (1 if no clones) */
l_int32 xres; /* image res (ppi) in x direction */
/* (use 0 if unknown) */
l_int32 yres; /* image res (ppi) in y direction */
/* (use 0 if unknown) */
l_int32 informat; /* input file format, IFF_* */
char *text; /* text string associated with pix */
struct PixColormap *colormap; /* colormap (may be null) */
l_uint32 *data; /* the image data */
};
while QImage offers me a method like this:
http://developer.qt.nokia.com/doc/qt-4.8/qimage.html#QImage-7
QImage ( const uchar * data,
int width,
int height,
int bytesPerLine,
Format format )
I assume I cant just copy the data from the PIX to the QImage when calling the constructor. I guess I need to fill the QImage Pixel by Pixel, but actually I dont know how? Do I need to loop through all the coordinates? How do I regard the bit depth? Any ideas here?
I use this for conversion QImage to PIX:
PIX* TessTools::qImage2PIX(QImage& qImage) {
PIX * pixs;
l_uint32 *lines;
qImage = qImage.rgbSwapped();
int width = qImage.width();
int height = qImage.height();
int depth = qImage.depth();
int wpl = qImage.bytesPerLine() / 4;
pixs = pixCreate(width, height, depth);
pixSetWpl(pixs, wpl);
pixSetColormap(pixs, NULL);
l_uint32 *datas = pixs->data;
for (int y = 0; y < height; y++) {
lines = datas + y * wpl;
QByteArray a((const char*)qImage.scanLine(y), qImage.bytesPerLine());
for (int j = 0; j < a.size(); j++) {
*((l_uint8 *)lines + j) = a[j];
}
}
return pixEndianByteSwapNew(pixs);
}
And this for conversion PIX to QImage:
QImage TessTools::PIX2QImage(PIX *pixImage) {
int width = pixGetWidth(pixImage);
int height = pixGetHeight(pixImage);
int depth = pixGetDepth(pixImage);
int bytesPerLine = pixGetWpl(pixImage) * 4;
l_uint32 * s_data = pixGetData(pixEndianByteSwapNew(pixImage));
QImage::Format format;
if (depth == 1)
format = QImage::Format_Mono;
else if (depth == 8)
format = QImage::Format_Indexed8;
else
format = QImage::Format_RGB32;
QImage result((uchar*)s_data, width, height, bytesPerLine, format);
// Handle pallete
QVector<QRgb> _bwCT;
_bwCT.append(qRgb(255,255,255));
_bwCT.append(qRgb(0,0,0));
QVector<QRgb> _grayscaleCT(256);
for (int i = 0; i < 256; i++) {
_grayscaleCT.append(qRgb(i, i, i));
}
if (depth == 1) {
result.setColorTable(_bwCT);
} else if (depth == 8) {
result.setColorTable(_grayscaleCT);
} else {
result.setColorTable(_grayscaleCT);
}
if (result.isNull()) {
static QImage none(0,0,QImage::Format_Invalid);
qDebug() << "***Invalid format!!!";
return none;
}
return result.rgbSwapped();
}
This code accepts a const QImage& parameter.
static PIX* makePIXFromQImage(const QImage &image)
{
QByteArray ba;
QBuffer buf(&ba);
buf.open(QIODevice::WriteOnly);
image.save(&buf, "BMP");
return pixReadMemBmp(ba.constData(), ba.size());
}
I do not know the Leptonica Library, but I had a short look at the documentation and found the documentation about the PIX structure. You can create a QImage from the raw data and convert this to a QPixmap with convertFromImage.
Well I could solve the problem this way:
Leptonica offers a function
l_int32 pixWriteMemBmp (l_uint8 **pdata, size_t *psize, PIX *pix)
With this function you can write into the memory instead of a filestream. Still ( in this example ) the Bmp Header and format persists ( there are the same functions for other image formats too ).
The corresponding function from QT is this one:
bool QImage::loadFromData ( const uchar * data, int len, const char * format = 0 )
Since the the Header persits I just need to pass the data ptr and the size to the loadFromData function and QT does the rest.
So all together it would be like this:
PIX *m_pix;
FILE * pFile;
pFile = fopen( "PathToFile", "r" );
m_pix = pixReadStreamBmp(pFile); // If other file format use the according function
fclose(pFile);
// Now we have a Pix object from leptonica
l_uint8* ptr_memory;
size_t len;
pixWriteMemBmp(&ptr_memory, &size, m_pix);
// Now we have the picture somewhere in the memory
QImage testimage;
QPixmap pixmap;
testimage.loadFromData((uchar *)ptr_memory,len);
pixmap.convertFromImage(testimage);
// Now we have the image as a pixmap in Qt
This actually works for me, tho I don't know if there is a way to do this backwards so easy. ( If there is, please let me know )
Best Regards
You can save your pixmap to RAM instead of file (use QByteArray to store the data, and QBuffer as your I/O device).
I need to create a CImage from a byte array (actually, its an array of unsigned char, but I can cast to whatever form is necessary). The byte array is in the form "RGBRGBRGB...". The new image needs to contain a copy of the image bytes, rather than using the memory of the byte array itself.
I have tried many different ways of achieving this -- including going through various HBITMAP creation functions, trying to use BitBlt -- and nothing so far has worked.
To test whether the function works, it should pass this test:
BYTE* imgBits;
int width;
int height;
int Bpp; // BYTES per pixel (e.g. 3)
getImage(&imgBits, &width, &height, &Bpp); // get the image bits
// This is the magic function I need!!!
CImage img = createCImage(imgBits, width, height, Bpp);
// Test the image
BYTE* data = img.GetBits(); // data should now have the same data as imgBits
All implementations of createCImage() so far have ended up with data pointing to an empty (zero filled) array.
CImage supports DIBs quite neatly and has a SetPixel() method so you could presumably do something like this (uncompiled, untested code ahead!):
CImage img;
img.Create(width, height, 24 /* bpp */, 0 /* No alpha channel */);
int nPixel = 0;
for(int row = 0; row < height; row++)
{
for(int col = 0; col < width; col++)
{
BYTE r = imgBits[nPixel++];
BYTE g = imgBits[nPixel++];
BYTE b = imgBits[nPixel++];
img.SetPixel(row, col, RGB(r, g, b));
}
}
Maybe not the most efficient method but I should think it is the simplest approach.
Use memcpy to copy the data, then SetDIBits or SetDIBitsToDevice depending on what you need to do. Take care though, the scanlines of the raw image data are aligned on 4-byte boundaries (IIRC, it's been a few years since I did this) so the data you get back from GetDIBits will never be exactly the same as the original data (well it might, depending on the image size).
So most likely you will need to memcpy scanline by scanline.
Thanks everyone, I managed to solve it in the end with your help. It mainly involved #tinman and #Roel's suggestion to use SetDIBitsToDevice(), but it involved a bit of extra bit-twiddling and memory management, so I thought I'd share my end-point here.
In the code below, I assume that width, height and Bpp (Bytes per pixel) are set, and that data is a pointer to the array of RGB pixel values.
// Create the header info
bmInfohdr.biSize = sizeof(BITMAPINFOHEADER);
bmInfohdr.biWidth = width;
bmInfohdr.biHeight = -height;
bmInfohdr.biPlanes = 1;
bmInfohdr.biBitCount = Bpp*8;
bmInfohdr.biCompression = BI_RGB;
bmInfohdr.biSizeImage = width*height*Bpp;
bmInfohdr.biXPelsPerMeter = 0;
bmInfohdr.biYPelsPerMeter = 0;
bmInfohdr.biClrUsed = 0;
bmInfohdr.biClrImportant = 0;
BITMAPINFO bmInfo;
bmInfo.bmiHeader = bmInfohdr;
bmInfo.bmiColors[0].rgbBlue=255;
// Allocate some memory and some pointers
unsigned char * p24Img = new unsigned char[width*height*3];
BYTE *pTemp,*ptr;
pTemp=(BYTE*)data;
ptr=p24Img;
// Convert image from RGB to BGR
for (DWORD index = 0; index < width*height ; index++)
{
unsigned char r = *(pTemp++);
unsigned char g = *(pTemp++);
unsigned char b = *(pTemp++);
*(ptr++) = b;
*(ptr++) = g;
*(ptr++) = r;
}
// Create the CImage
CImage im;
im.Create(width, height, 24, NULL);
HDC dc = im.GetDC();
SetDIBitsToDevice(dc, 0,0,width,height,0,0, 0, height, p24Img, &bmInfo, DIB_RGB_COLORS);
im.ReleaseDC();
delete[] p24Img;
Here is a simpler solution. You can use GetPixelAddress(...) instead of all this BITMAPHEADERINFO and SedDIBitsToDevice. Another problem I have solved was with 8-bit images, which need to have the color table defined.
CImage outImage;
outImage.Create(width, height, channelCount * 8);
int lineSize = width * channelCount;
if (channelCount == 1)
{
// Define the color table
RGBQUAD* tab = new RGBQUAD[256];
for (int i = 0; i < 256; ++i)
{
tab[i].rgbRed = i;
tab[i].rgbGreen = i;
tab[i].rgbBlue = i;
tab[i].rgbReserved = 0;
}
outImage.SetColorTable(0, 256, tab);
delete[] tab;
}
// Copy pixel values
// Warining: does not convert from RGB to BGR
for ( int i = 0; i < height; i++ )
{
void* dst = outImage.GetPixelAddress(0, i);
const void* src = /* put the pointer to the i'th source row here */;
memcpy(dst, src, lineSize);
}