Hello Anna Srikrishna Sri,
I hope you saw my previous post how to change the boot logo, else you can follow the below step,
Step1:
First you need to change the image format from ( * = your image name)
first change the .bmp file to .png file then do below steps.
-->pngtopnm linuxlogo.png > linuxlogo.pnm
-->pnmquant 224 linuxlogo.pnm > linuxlogo224.pnm
-->pnmtoplainpnm linuxlogo224.pnm > linuxlogo224.ppm
Step2:
Replace the your converted *.ppm file with original *.ppm file in build/tmp/work/wandboard_quad-poky-linux-gnueabi/u-boot-fslc/v2014.10gitAUTOINC5fd0b607d0-r0/git/tools/logos.
Step 3:
Recompile your Image,
After doing the above steps please let me know.
BR
Nandish SG