basic image processing module

[simplesi]

Is there a basic image reader module in default Pi Python 2 setup?

I'm just looking to reading in a image - reduce it in size to 8x8 and display it on a Unicorn Hat

Simon

[DirkS]

Pillow (formerl PIL): http://pillow.readthedocs.org/
or ImageMagick

Gr.
Dirk.

[simplesi]

I was wondering if there was anything basic that is installed by default?

Simon

[DirkS]

I was wondering if there was anything basic that is installed by default?

Not that I'm aware of...

Gr.
Dirk.

[gordon77]

What kind of image are you reducing to 8x8 ?

Expecting something viewable ?

[paddyg]

You could probably use numpy which has been bundled with the standard raspbian. BUT if you haven't used it much already you probably won't find it 'basic' (though I would recommend getting to grips with it). See some discussion here http://www.raspberrypi.org/forums/viewt ... ge#p532741
Pillow is your best bet.

[simplesi]

I don't think (or at least can't find) numpy reads image files

Simon

[gordon77]

How about just using pygame to load the image, then pygame.transform to resize it, possible taking the average of the 64 areas and rebuilding the 8x8 image.

How do you display it on the hat ?

[simplesi]

I need (want) a module that doesn't need installing by the user for ScratchGPO to read in an image and then display it on a led matrix

Its just occured to me that maybe I bodge things by calling bash image commands

Simon

[simplesi]

Well - i've resorted to just reading bytes from an 8x8 bmp file to start with so I'm relying on external progs to resize/convert for me buts its a start

https://vine.co/u/968241109107089408

[gordon77]

I need (want) a module that doesn't need installing by the user for ScratchGPO to read in an image and then display it on a led matrix

Its just occured to me that maybe I bodge things by calling bash image commands

Simon

Pygame doesn't need installing with python 2.7, is that what you mean or do you mean installing even a python program?

[simplesi]

No - if pygame is installed by default - I'll give it a go

Ta

Simon

[knute]

You are going to run into some interesting artifacts by scaling an image to 8x8. I'm not a Python programmer so I can't help you with that but it is a simple task in Java to scale an image. What do you need in the end, the RGB values of the 64 pixels?

[simplesi]

Got this working

Code: Select all

if self.bFindValue('image'):
                            
                                subprocess.Popen(['convert', '-resize', '8x8!', '+matte', '/home/pi/sghdev/scratch_gpio/' +self.value , '/home/pi/sghdev/scratch_gpio/sghimage.bmp'])
                                # When reading a binary file, always add a 'b' to the file open mode
                                with open('sghimage.bmp', 'rb') as f:
                                #with open(self.value + '.bmp', 'rb') as f:
                                    # BMP files store their width and height statring at byte 18 (12h), so seek
                                    # to that position
                                    f.seek(10)

                                    # The width and height are 4 bytes each, so read 8 bytes to get both of them
                                    bytes = f.read(4)

                                    # Here, we decode the byte array from the last step. The width and height
                                    # are each unsigned, little endian, 4 byte integers, so they have the format
                                    # code '<II'. See http://docs.python.org/3/library/struct.html for more info
                                    bmpdata = int(struct.unpack('<I', bytes)[0])
                                    print bmpdata

                                    # Print the width and height of the image
                                    print('Data starts at:  ' + str(bmpdata))
                                    #print('Image height: ' + str(size[1]))
                                    f.seek(bmpdata)
                                    for i in range(0,64):
                                        bytes = f.read(3)
                                        pixel = struct.unpack('BBB',  bytes)#[0]
                                        #pixel = struct.unpack('<I', bytes)[0]
                                        print i,pixel  
                                        self.matrixBlue,self.matrixGreen,self.matrixRed = pixel

                                        ym = int(int(i) / 8)
                                        xm  = i % 8
                                        #print "xm,ym" ,xm,ym
                                        #print self.matrixRed,self.matrixGreen,self.matrixBlue
                                        #print self.matrixMult,self.matrixLimit,self.matrixRangemax,led, ym, ym
                                        UH.set_pixel(xm,7 - ym,self.matrixRed,self.matrixGreen,self.matrixBlue)
                                    UH.show()   

Just need to make sure it works on a virgin Raspbian install

Simon

[paddyg]

could you do something like this which might be tidier:

Code: Select all

bytes = f.read(192)
pixel = struct.unpack('192B',  bytes)
pixel = numpy.array(pixel).reshape(8, 8, 3)
for i, p in enumerate(pixel):
  for j, pp in enumerate(p[::-1]):
    UH.set_pixel(i, j, pp[0], pp[1], pp[2])

[simplesi]

Ta - I've ended up with this (saves using numpy)

Code: Select all

                                    bytes = f.read(192)
                                    pixel = struct.unpack('192B',  bytes)
                                    print "pixel",pixel
                                    for i in range(0,64):
                                        UH.set_pixel( i % 8, 7 - (i // 8), pixel[(i * 3) +2], pixel[(i * 3) +1], pixel[(i * 3) +0])