Yes, I read your forum voting comments. It is usually better to downsize images. Going up or down, before doing so, convert the item into a smart object. This wil help retain the resolution. Works great downsizing, but to upsize go in increments, the smaller the increase the better (until you can see that the resolution is dropping). If it needs a alittle help after that, try the smarten filters; smart sharpen or unsharp mask can usually help a little.