convert pdf files to text

convert.py

def pdf_to_str(filename, resolution=600):
    try:
        with wand.image.Image(filename=filename, resolution=resolution) as img:
            
            img.type = 'grayscale'
            img.format = 'jpeg'
            img.compression_quality = 100
            directory = tempfile.mkdtemp()

            output_path = os.path.join(directory, filename[:-4] + '.jpg')
            with img.convert('jpeg') as converted:
                converted.save(filename=output_path)

            text = ocr_directory(directory)
            shutil.rmtree(directory)
        
            return text
            
    except: 
        return None

def img_to_str(img_path):
    try:
        return pytesseract.image_to_string(Image.open(img_path))
    except:
        return None
    
def ocr_directory(directory):
    filenames = glob.glob(os.path.join(directory, '*'))
    return '\n'.join((img_to_str(image) for image in filenames))

        
print pdf_to_str('all.pdf')