While using Linear, Anisotropic texture filtering it does a nice job scaling but also blurs.
I don’t mind the blur as much, however it also dims the colors slightly.
I tied using gama to make it brighter but It seems it’s already at the highest level.
Is there anyway to make the colors more vivid or brighter after applying texture filtering?
I don’t know if this applies to your situation, but you can do alpha and color mods to textures and surfaces… Search for SDL_SetTextureColorMod for textures…
You can also change surface/texture blend modes to additive… Although that may increase brightness by way too much… Search for SDL_SetTextureBlendMode for textures…
Probably wont help. 
My best advice would be to either 1) Deal with it (let it be) or 2) Brighten the images in an image manipulation program.
SDL’s gamma is set maxed out at initialization? Or your monitors gamma is maxed? Or your video driver’s gamma is maxed? So many to deal with.
You can also look into SDL_SetWindowBrightness, and SDL_SetWindowGammaRamp to see if they may help you out.