docs(tjpgd): update tjpgd docs (#4959)

docs/libs/tjpgd.rst

@@ -2,43 +2,28 @@
 TJPGD decoder
 =============
 
-Allow the use of JPG images in LVGL. Besides that it also allows the use
+Allow the use of JPG (JPEG) images in LVGL.
-of a custom format, called Split JPG (SJPG), which can be decoded in
-more optimal way on embedded systems.
 
 Overview
 --------
 
--  Supports both normal JPG and the custom SJPG formats.
+-  JPG is decoded in 8x8 tiles.
--  Decoding normal JPG consumes RAM with the size of the whole
+-  Read from file and C array are implemented.
-   uncompressed image (recommended only for devices with more RAM)
+-  Only the required portions of the JPG images are decoded,
--  SJPG is a custom format based on "normal" JPG and specially made for
-   LVGL.
--  SJPG is 'split-jpeg' which is a bundle of small jpeg fragments with
-   an sjpg header.
--  SJPG size will be almost comparable to the jpg file or might be a
-   slightly larger.
--  File read from file and c-array are implemented.
--  SJPEG frame fragment cache enables fast fetching of lines if
-   available in cache.
--  By default the sjpg image cache will be image width \* 2 \* 16 bytes
-   (can be modified)
--  Currently only 16 bit image format is supported (TODO)
--  Only the required portion of the JPG and SJPG images are decoded,
    therefore they can't be zoomed or rotated.
 
 Usage
 -----
 
 If enabled in ``lv_conf.h`` by :c:macro:`LV_USE_TJPGD` LVGL will register a new
-image decoder automatically so JPG and SJPG files can be used directly
+image decoder automatically so JPG files can be used directly
 as image sources. For example:
 
 .. code:: c
 
    lv_image_set_src(my_img, "S:path/to/picture.jpg");
 
-Note that, a file system driver needs to registered to open images from
+Note that a file system driver needs to be registered to open images from
 files. Read more about it :ref:`file-system` or just
 enable one in ``lv_conf.h`` with ``LV_USE_FS_...``
 
@@ -51,35 +36,6 @@ Converting JPG to C array
 -  Use lvgl online tool https://lvgl.io/tools/imageconverter
 -  Color format = RAW, output format = C Array
 
-Converting JPG to SJPG
-~~~~~~~~~~~~~~~~~~~~~~
-
-python3 and the PIL library required. (PIL can be installed with ``pip3 install pillow``)
-
-To create SJPG from JPG: - Copy the image to convert into
-``lvgl/scripts`` - ``cd lvgl/scripts`` -
-``python3 jpg_to_sjpg.py image_to_convert.jpg``. It creates both a C
-files and an SJPG image.
-
-The expected result is:
-
-.. code:: sh
-
-   Conversion started...
-
-   Input:
-           image_to_convert.jpg
-           RES = 640 x 480
-
-   Output:
-           Time taken = 1.66 sec
-           bin size = 77.1 KB
-           walpaper.sjpg           (bin file)
-           walpaper.c              (c array)
-
-   All good!
-
-
 Example
 -------