Improve documentation

Author: neurolabusc

README.md

@@ -49,7 +49,7 @@ Likewise, if you are compiling on Windows using cmake:
 ```
 git clone https://github.com/rordenlab/niimath.git
 cd niimath & mkdir build & cd build & cmake ..
-msbuild niimath.sln
+cmake --build .
 ```
 Alternatively, you can compile the software by running the terminal command `make` from the project's `src` folder if you are running Linux (or execute `windows.bat` if you are running Windows):
 

library/README.md

@@ -1,6 +1,6 @@
 ## About
 
-`niimath` is a high-performance command-line tool for manipulating NIfTI images. Because `niimath` is so fast, the main bottleneck in many workflows is disk I/O. To enable efficient workflows, niimath supports reading from and writing to standard input/output streams using the special filename `-`.
+`niimath` is a high-performance command-line tool for manipulating NIfTI images. Because `niimath` is so fast, the main bottleneck in many workflows is disk I/O. To enable efficient workflows, niimath supports reading from and writing to standard input/output streams using the special filename `-`. It is important to note that both the input and output must be single-file NIfTI-1 images (e.g. `img.nii`). Compressed files (e.g. `img.nii.gz`) must be decompressed prior to using the memory stream input.
 
 This streaming capability is especially useful for chaining tools together without writing intermediate results to disk. For example:
 
@@ -31,4 +31,11 @@ python read_stdin.py
 
 # Pipe a NIfTI image to niimath and capture the output via stdout, fully in memory
 python read_write_stream.py
+
+# Use nibabel to_bytes() and from_bytes() to call niimath using pipes
+python nibabel_niimath.py
 ```
+
+## Limitations
+
+These features are currently only supported on Unix operating systems (Linux and MacOS). Memory piping works differently on Windows computers.

src/niftilib/nifti2_io.c

@@ -5682,7 +5682,7 @@ nifti_image *nifti_image_read( const char *hname , int read_data )
    /**- read the data if desired, then bug out */
    if( read_data ){
       if (isStdIn) {
-        nim->iname = strdup("-");
+        nim->iname = nifti_strdup("-");
         if (ni_ver != 1) {
             fprintf(stderr,"piped input only supports NIFTI-1\n");
             return NULL;