.. _png_decode:

PNG decode
====================

Overview
--------

PNG decoding example project demonstrates how to decode a PNG file using LODEPNG software PNG library.

Board Setting
-------------

- Connect the **USB disk**  to the development board ``usb0`` (Attention: The `Cluster Size` of the USB disk can't exceed 32KB, it is recommended that the format parameter is FAT32/32KB), or insert the **SD memory card**  into the development board ``SD card``

  .. image:: ../../../../../samples/image/common/doc/UDisk_Format.png
     :alt: UDisk_Format

- Connect **LCD screen**  to development board

Configuration
-------------

- File `CMakeLists.txt`.

  - ``set (PNG_USE_SDCARD 1)``  to read png file (.png) from SD card or ``set (PNG_USE_UDISK 1)``  to read png file (.png) from u-disk. These options are exclusive.

Supported picture formats
-------------------------

- Supports standard PNG images

Image size supported by this routine
------------------------------------

- png file size is expected to be less than 1MB

Running the example
-------------------

- Configure storage in CMakeLists.txt, default is PNG_USE_SDCARD.

- Put png files (with .png) into target storage

- Connect LCD pannel and storage to board

- Power on the board

- Download built elf into development board and run the demo

- If everything goes well, jpeg files stored in the target storage will be show on LCD pannel one by one.