That’s a good start, but I don’t think that’s a power of 2. Computers do their best computing in powers of 2, so like 2^x, or 2, 4, 8, 16, 32, etc. I’ve found 256×256 works well for me, maybe 512×512 could work, too. Other than that, I don’t know what to tell you. Hopefully someone will come along and help. Just keep trying your best and hopefully an answer will appear. Best of luck!