Using Fstream To Load A Jpg Into A Mat Type

I have this function which i used to save a folder of images into a mat file as a database.

Using fstream to load a jpg into a mat type.

If the stream is already associated with a file i e it is already open calling this function fails. The idx argument is supported only for multi image gif cur ico and hdf4 files. Input output stream class to operate on files. You read information from a file into your program using the stream extraction operator just as you use that operator to input information from the keyboard.

File streams are associated with files either on construction or by calling member open. Since after all it doesn t make any sense to write an entire mat file to a jpeg only to write a variable from a mat file. For a gif file if idx is 1 5 then imread returns only the first five frames. We can see that the pixel values are converted from unsigned integers to 32 bit floating point values and in this case converted to the array format height width channels finally the image is converted back into pil format.

After you decide on an export format you can use the saveas function to perform the task. Because joint photographic experts group jpeg files are common on most platforms the example uses a jpeg. The only difference is that you use an ifstream or fstream object instead of the cin object. Objects of this class maintain a filebuf object as their internal stream buffer which performs input output operations on the file they are associated with if any.

Image to read specified as an integer scalar or for gif files a vector of integers. Read and write example. And it has been observed that when the conversion produces a single field the labelled temperatures are inaccurate whereas when 5 fields are produced as is the case when using the load filename mat command the temperatures are correct. Running the example first loads the photograph in pil format then converts the image to a numpy array and reports the data type and shape.

In this case you type saveas gcf bar1 jpeg jpg and press enter. The jpg images converted to mat files are used to plot labelled temperature contours. The most important parameter is the output type. Opens the file identified by argument filename associating it with the stream object so that input output operations are performed on its content argument mode specifies the opening mode.

The file association of a stream is kept by its internal stream buffer. When reading multiple frames from the same gif file specify idx as a. This is an instantiation of basic fstream with the following template parameters. This code grabs whatever variable it finds first in the mat and tries to write it as jpeg.