im using gdi+ to output my images.
i tried to use the keyword new but it didn't work.
shot(L"image name") = new Image;
that didn't work any other ideas how to make it work
Something like this seems a lot more likely:
Image *image_object = new Image(L"Image Name");
Except that there's a pretty decent chance you don't want to allocate the Image object dynamically at all -- unless you really do, you generally want to just define an object with automatic storage duration:
Image image_object(L"Image Name");
The GDI+ Image class is not default constructible. You have to supply some parameters to the constructor in order to create one - see here.
You may well be better off using Gdiplus::Bitmap, which derives from Image. That seems more likely if you're trying to output it.
Related
I am trying to resize images using Magick++ api in C++. I have used the following code and it is working good.
Image second = image;
Geometry newSize = Geometry(69,69);
// Resize without preserving Aspect Ratio
newSize.aspect(true);
second.resize(newSize);
The result is good but I need to know the default filter type it is using as I am not giving any other argument in resize() function. I have searched in documentation but could not find much.
Thank you for the help.
In MagickCore libary, the ReszieImage method does default to LanczosFilter.
From MagickCore/resize.c
filter_type=LanczosFilter;
if (filter != UndefinedFilter)
filter_type=filter;
However in Magick++ the default filterType is UndefinedFilter. Take the following..
Magick::Image image("rose:");
std::cout << image.filterType() << std::endl;
//=> 0
IMHO, always define the filter with Magick::image::filterType( const Magick::FilterTypes filterType_ ). It'll help when your reading the code in the future.
I have got the answer to my own question. It was Lanczos resampling.
A very good magick++ documentation can be found here.
Migrating some code from VTK 5.10 to 6.1, I have several code pieces like this:
vtkSmartPointer<vtkImageData> img = vtkSmartPointer<vtkImageData>::New();
// ... initialize img somehow, e.g. copy from other image:
img->DeepCopy(otherImg);
img->SetInformation(otherImg->getInformation());
// the problematical statement:
img->Update();
At the call to Update(), the compiler now complains that there isn't such a function (anymore).
The migration site from VTK doesn't really tell me too much about that - I believe this falls into the section Removal of Data Objects’ Dependency on the Pipeline , but as it's no Algorithm which is filling my image, I can't call update on an algorithm.
Similar goes for custom-filled vtkPolyData objects.
My question now is: Is the call to Update not necessary (anymore?), can I just remove it? Or by what would I need to replace it?
I have to say I'm relatively new to vtk, so if there's something fundamentally simple that I'm missing I'd be glad if you could point it out to me!
I think you've been meaning to call Modified() on your image rather than Update().
Apparently they already answered your question on VTK:
http://www.vtk.org/Wiki/VTK/VTK_6_Migration/Removal_of_Update
I'm trying to do the following trick:
I have IDataObject* to be set into the clipboard, so I'm using OleSetClipboard() to set it into the clipboard.
I have another CLIPFORMAT I want to add to the clipboard, but I can't do it with OleSetClipboard() because the IDataObject* I receive does not implement SetData() method. So, to overcome this limitation I OpenClipboard() with GetClipboardOwner(), this way, I can SetClipboardData() to the clipboard without EmptyClipboard() first.
Now, it all works well, but what happens is that OleGetClipboard() does not return the data I placed in the clipboard using SetClipboardData(), but I can using GetClipboardData().
I can imagine why this happens (It just returns the IDataObject*), so I tried to OleFlushClipboard() to delete the IDataObject*, and OleGetClipboard() again to let the OS rebuild a new IDataObject*, and it still didn't contain the CLIPFORMAT added by SetClipboardData().
Does anyone have any idea how to overcome this issue? or a different trick? or even explain why it works this way? Thanks
I just tried this (on Windows 7) and it appears to work but only cross-process:
In a different process to the clipboard owner, OleGetClipboard returns a data object that contains all of the formats (i.e. the original formats from the data object and the extra ones added to the clipboard).
In the same process, OleGetClipboard always returns a data object that does not contain the extra clipboard formats.
In both cases, calling OleFlushClipboard makes no difference.
Anyway, this doesn't seem like a terribly robust solution. What you can do instead is create your own data object that responds to the formats it knows about and delegates other formats to the original data object. The EnumFormatEtc method would combine formats from both objects, and so on. This article has the skeleton of a simple data object you could extend.
I am new to C++ and I am trying to create a list of cv::Mat.
This could allocate quite a lot of memory, but I only have around ten small Mat's to load in the list.
I made this code, but not sure why it is not working.
void Utils::getFramesFromVideo(std::string file,std::list<cv::Mat>& listMatOutput) {
cv::VideoCapture* videoCapture = new cv::VideoCapture(file);
bool hasImage = false;
cvNamedWindow("WhileReading", 1);
do {
cv::Mat frame;
hasImage = videoCapture->read(frame);
if (hasImage) {
listMatOutput.push_back(frame);
imshow("WhileReading", frame);
waitKey(0);//give some time to see the frame (debug)
}
} while (hasImage);
cvNamedWindow("AfterReading", 2);
for (std::list<Mat>::const_iterator iterator = listMatOutput.begin();
iterator != listMatOutput.end(); iterator++) {
imshow("AfterReading", *iterator);
waitKey(0);//give some time to see the frame (debug)
}
videoCapture->release();
}
The first loading is displaying the frames correctly, but in the second window (AfterReading) the image is black with red stripes.
Could someone please give some advice?
The list format is an STL container, meaning that you've got some things to keep in mind to work with it. push_back() is the preferred method of adding instances to the container, much like using an iterator is the preferred method of accessing the elements of the list. If you try to directly set an element of the list to a cv::Mat() you're working on, then a) you need to know exactly what sort of wrapping the list is doing to each instance, so you can do it properly yourself, and b) you're defeating the purpose of using an STL container in the first place, which is to abstract away the details of the list.
You don't necessarily need to use the frame.clone() call in your code, as this creates a deep copy of the image and takes up precious resources. I know that I've used std::vector<cv::Mat> in the past without having to make deep copies for each element in the vector, so I assume that you should be able to pass the Mat itself to a list. Consult the C++ documentation on STL lists.
Another thing you might consider, if low memory usage and speed of access through the list is a concern, and your number of images is low, is a list of image pointers. Keep your images stored as individual cv::Mat instances, and make your list of type std::list<cv::Mat*>, passing the handle of the image to the push_back() call. Of course, with this method, your images will not be 'thread safe' because they will be stored in one place, but called and worked on from another. I hope this shed a little light on your inquiry.
I tried all sort of things, like changing to pointers or vectors and checking for code optimizations on GCC. Then after trying to clone cv::Mat it worked:
listMatOutput.push_back(frame.clone());
Would be glad if anyone could tell me why and suggest a better way of doing, so I can choose a better answer then my own.
I'm currently trying to figure out how to use the Generic Image Library included in Boost. Right now, I just want to use the library to store pixel data and use the Image IO to write PNGs. I'm having trouble understanding just how to set up the object however.
The hpp says
image(const point_t& dimensions,
std::size_t alignment=1) : _memory(0), _align(alignment) {
allocate_and_default_construct(dimensions);
}
but I cannot find any references to point_t except a type_def for view_t::point_t to point_t.
Also, the tutorial found with the GIL seems to only include writing filters and generic algorithms, and thus each function example they provide has a source image view, from which they take the dimensions.
Am I going about this the wrong way? Or is there something I've missed completely?
Thanks in advance
Edit: I don't know if anyone cares, or has read this, but for the record, I just used the boost interleaved image function to create a PNG. It's not exactly the same solution, but it works for my applications.
it sounds like you solved your problem in the meantime, but just for the record... here are some pointers to information about your problem:
First of all you may have missed the second constructor of boost::gil::image, which offers explicit access to the horizontal and vertical dimensions without the need of the point_t:
image(x_coord_t width, y_coord_t height,
std::size_t alignment=0,
const Alloc alloc_in = Alloc()) : _memory(0), _align_in_bytes(alignment), _alloc(alloc_in) {
allocate_and_default_construct(point_t(width,height));
}
point_t will most likely refer to the point2 class template defined in boost/gil/utilities.hpp.
In general you should check the complete documentation of Boost GIL for all questions not mentioned in the tutorial. For a deeper understanding of the library it is absolutely necessary to get familiar with the Design Guide and the Doxygen Documentation.