AM62P: Consultation on Premultiplied Alpha setup for the DSS module

Part Number: AM62P

Tool/software:

In The TI official document spruj83a.pdf, the setting of the PREMULTIPLYALPHA bit determines whether the A in The image ARGB works, but in the configuration, no matter what value I set for this bit, this alpha always works.So I would like to ask if there are any other configurations that have an impact on alpha.

  • Hi,
    Can you share how you are testing this? Have you taken care of the note in the image shared by you?

  • This is part of my image data. 0x00 in the image represents transparency

    This is my test code. I need to change the transparency from 0x00 to oxFF in order to display the image

    If the 0x00 data in the image remains unchanged, only by modifying the PREMULTIPLYALPHA in the register, the image cannot be displayed regardless of whether it is set to 1 or 0

  • Hi,
    I didn't completely understand your observation, can you fill in the following for me:
    a.  PREMULTIPLYALPHA = 0 (Default value -> DSS will multiply per pixel alpha along with global alpha for each pixel)
               1. Observation when each alpha value is 0x00 : ?
               2. Observation when each alpha value is 0xff : ?

    b. PREMULTIPLYALPHA = 1 (DSS will only multiply with global alpha for each pixel)
               1. Observation when each alpha value is 0x00 : ?
               2. Observation when each alpha value is 0xff : ?