| from io import BytesIO |
| import base64 |
| from .png import Writer, from_array |
|
|
| try: |
| from PIL import Image |
|
|
| pil_imported = True |
| except ImportError: |
| pil_imported = False |
|
|
|
|
| def image_array_to_data_uri(img, backend="pil", compression=4, ext="png"): |
| """Converts a numpy array of uint8 into a base64 png or jpg string. |
| |
| Parameters |
| ---------- |
| img: ndarray of uint8 |
| array image |
| backend: str |
| 'auto', 'pil' or 'pypng'. If 'auto', Pillow is used if installed, |
| otherwise pypng. |
| compression: int, between 0 and 9 |
| compression level to be passed to the backend |
| ext: str, 'png' or 'jpg' |
| compression format used to generate b64 string |
| """ |
| |
| if compression < 0 or compression > 9: |
| raise ValueError("compression level must be between 0 and 9.") |
| alpha = False |
| if img.ndim == 2: |
| mode = "L" |
| elif img.ndim == 3 and img.shape[-1] == 3: |
| mode = "RGB" |
| elif img.ndim == 3 and img.shape[-1] == 4: |
| mode = "RGBA" |
| alpha = True |
| else: |
| raise ValueError("Invalid image shape") |
| if backend == "auto": |
| backend = "pil" if pil_imported else "pypng" |
| if ext != "png" and backend != "pil": |
| raise ValueError("jpg binary strings are only available with PIL backend") |
|
|
| if backend == "pypng": |
| ndim = img.ndim |
| sh = img.shape |
| if ndim == 3: |
| img = img.reshape((sh[0], sh[1] * sh[2])) |
| w = Writer( |
| sh[1], sh[0], greyscale=(ndim == 2), alpha=alpha, compression=compression |
| ) |
| img_png = from_array(img, mode=mode) |
| prefix = "data:image/png;base64," |
| with BytesIO() as stream: |
| w.write(stream, img_png.rows) |
| base64_string = prefix + base64.b64encode(stream.getvalue()).decode("utf-8") |
| else: |
| if not pil_imported: |
| raise ImportError( |
| "pillow needs to be installed to use `backend='pil'. Please" |
| "install pillow or use `backend='pypng'." |
| ) |
| pil_img = Image.fromarray(img) |
| if ext == "jpg" or ext == "jpeg": |
| prefix = "data:image/jpeg;base64," |
| ext = "jpeg" |
| else: |
| prefix = "data:image/png;base64," |
| ext = "png" |
| with BytesIO() as stream: |
| pil_img.save(stream, format=ext, compress_level=compression) |
| base64_string = prefix + base64.b64encode(stream.getvalue()).decode("utf-8") |
| return base64_string |
|
|
