About color format and platform package

Question

Hi, EW Team:

    I am doing a project of screen size 1280x360, with VGLite RGBA8888 platform package for RT1170. There is a project in RFQ, which has a double size screen.

    To guarantee graphic performance, I have 2 options:

   1. Use bigger RAM. Use 2 cores of RT1170 and assign some non-graphic computing to M4 core.

   2. Use RGB565 platform package and retain current hardware design of lower cost.

   But the RGB565 platform package is less expressive as RGBA8888. When the color has a gradient over space, color bars will be seen in the screen.

   Can this problem be solved? Maybe by asking image resources of RGB565 format from customer.

   Another observation is that data source files generated by the 2 platform package  from one image have the same size. It seems that platform package just means framebuffer format. Internal computing are the same for them?

    Thank you.

    Best regards.

Stephen.

Answer 1

Hello Stephen,

when comparing the two color formats of the Platform Packages RGB565 and RGBA8888, the framebuffer format is different (see Supported Frame Buffer and Bitmap Formats). This means, all graphics operations are done into this color format of the Platform Package. This does not have any impact to the format of the resources that you are using in your project - this is what you already observed.

Please note that you can explicitly control the bitmap format of your bitmap resource.

In case your GUI design consists of many gradients, the usage of RGB565 will cause noticeable color steps. In order to avoid that, you can use bitmaps with dithered content.

In case you are using RGBA8888 color format, please keep in mind that the double amount of RAM is required for the framebuffers, and that the requested memory bandwidth by eLCDIF is doubled.

Best regards,

Manfred. 

Comments

Hi, Manfred:

     You said that all graphics operations are done into this color format of the Platform Package, does it means that besides eLCDIF bandwidth, all memory bandwidths consumed by heap are also doubled?

     I have tried your suggestion about color gradient with the linked image. The color steps are still noticeable when RGB565 is used. 

Image_with_gradient

Best regards.

Stephen

---

Hi Stephen,

please note that the eLCDIF is updating the display permanently and the amount of data is the double in case of RGBA8888. For the graphics composition, also the double amount of data has to be written - but only for each display update and only for the affected area.

Best regards,

Manfred.