读取二进制文件只打印零

Question

I am trying to read a 3D image binary file and display a slice of the 3D image in python.The format is int16 with big endian. The file extension is .rec . I have the following piece of code:

struct_fmt = '>h' # big-endian,signed int16
struct_len = struct.calcsize(struct_fmt)
struct_unpack = struct.Struct(struct_fmt).unpack_from

results = []
with open('test.rec', "rb") as f:
    while True:
        data = f.read(struct_len)
        if not data: break
        s = struct_unpack(data)
        results.append(s)

img3d = np.array(results)
img3d = img3d.reshape(401,401,326)
np.save('output.npy',img3d)
image = np.load('output.npy')
fig,ax=plt.subplots()
output_slice=image[:,190,:]
ax.imshow(output_slice,cmap='gray')
ax.axis('off')
plt.show()

But I get all the voxel values as 0. And the image is black. What am I missing?

Answer 1

I found the solution. In matplotlib, the convention is (z,x,y), so that means the smaller resolution comes first. So it means there are 326 projections of 401x401 2D images. So actually the voxels values were getting misplaced. so i had a distorted image. Also plotting a histogram of voxel values helped a lot. Just used plt.hist(img_arry.ravel(),bins=50) to plot a histogram.