Pinephone A64 native resolution 1440x720 18:9 2:1

Display size: 5.32" × 2.66" = 14.16in² (13.52cm × 6.76cm = 91.36cm²) at 270.58 PPI, 0.0939mm dot pitch, 73215 PPI²

https://developer.toradex.com/linux-bsp/how-to/boot/splash-screen-on-u-boot/


* Inkscape

Load the svg to inkscape and export png


* Converting from PNG to BMP

U-Boot can read a specific image format. Use the following command to convert the PNG image to BPM.
SVG="Devuan-logo.svg"
PNG="Devuan-logo.png"
BMP="Devuan-logo.bmp"
inkscape --export-type="png" ${SVG}
convert ${PNG} -type Palette -colors 224 -depth 8 -compress none -verbose BMP3:${PNG}

SVG="Devuan-logo-swoosh.svg"
PNG="Devuan-logo-swoosh.png"
BMP="Devuan-logo-swoosh.bmp"
inkscape --export-type="png" ${SVG}
convert ${PNG} -type Palette -colors 224 -depth 8 -compress none -verbose BMP3:${BMP}


# The u-boot makefile sets the location of the logo image in LOGO_BMP
# It will look for logos/$(BOARD).bmp and logos/$(VENDOR).bmp so
# we can write it their instead.
# copy to the existing denx generic logo image location.
# tools/bmp_logo --gen-info ./tools/logos/denx.bmp > include/bmp_logo.h
# tools/bmp_logo --gen-bmp ./tools/logos/denx.bmp > include/bmp_logo_data.h
cp ~/${BMP} ${UBOOT_HOME}/tools/logos/denx.bmp


-----
* Using GIMP image dump

https://developer.ridgerun.com/wiki/index.php/How_to_change_uboot_splash_image



# Get image that you want to show in resolution smaller than your display resolution.
# Open the image using GIMP graphic application.
# Save the image using "save as" option.
# In the select box "Select File Type (by Extension)" select the format "c source code"
# Then you will get one windows with some options, in this window deselect all options (Use glibs types, use macros instead of struct, Use 1 byte run-length-encoding, Save alpha channel)
# Then save this file (changing the file extension from .c to .h) to
#* $DEVDIR/bootloader/uboot.*/src/board/davinci/common
# Change the variable value CONFIG_SPLASH_LOGO_FILE with the name of file used above. The CONFIG_SPLASH_LOGO_FILE configuration setting can be found in the Splash Screen section in your board file in the directory
#* $DEVDIR/bootloader/uboot.*/src/include/configs
# Clean and compile the bootloader

The form of the image-file must be similar to:

<syntaxhighlight lang="c">
/* GIMP RGB C-Source image dump (image.c) */

static const struct {
  unsigned int          width;
  unsigned int          height;
  unsigned int          bytes_per_pixel; /* 3:RGB, 4:RGBA */ 
  unsigned char         pixel_data[200 * 100 * 3 + 1];
} gimp_image = {
  200, 100, 3,
  "(\237\306(\237\306(\237\306(\237\306(\237\306(\237\306(\237\306(\237\306"
  "(\237\306(\237\306(\237\306(\237\306(\237\306(\237\306(\237\306(\237\306"
  "(\237\306(\237\306(\237\306(\237\306(\237\306(\237\306(\237\306(\237\306"
  "(\237\306(\237\306(\237\306(\237\306(\237\306(\237\306(\237\306(\237\306"
</syntaxhighlight>

Remember that normally the bootloader modifications are made using patches.