hi
i see that there is a refacrtion slider but i ask myself how that works when blender has no raytracing functions?
also somehow i have the impression that in 2.28 there is a very bad anti aliasing my renderings have often rough edges.
for the latter 2.28 will scale down rendered images differently than in previous versions, as in it will not do a pixel resize a good amount (1:2 1:3 1:4 … et. cetera), but will scale down as necescary (but not in a good manner), hence the problems.
the image should save fine, but I haven’t tested it.
– after edit —
no, it is not for refraction, as a rendering effect but as a lighting effect.
I think the value translates to something like how much the light bends when it enters a material before it comes out. (which is similar to subsurface scattering, but still considers the object solid: things shouldn’t become translucent when they are thinner). This and the diffuse properties can be used to tune the specular highlight to a great degree.
sorry i did not understand you anti aliasing explanation.
i understood that 2.28 scales images down a different way.
ok. so what do i have to do to get a decent result???
render to a size less than your screen resolution
There is no refraction slider, there is an IOR one, and is used for the Blinn shader to determine the amount of specular higlights.
I have not 
Stefano
About the refraction thing:
The Refr parameter for the Blinn shader influences how much specular light is reflected by the surface. This may seem counter-intuitive since it is supposedly an index of refraction, but in real life IoR’s effect not only the refractive properties of a material, but also the reflective properties of a material (and even solid objects have indices of refraction).
In the case of the Blinn shader, it only uses the IoR to calculate reflective stuff. If you want to learn more about how a material’s IoR effects its reflectivity, search around for info on the “fresnel effect”.
(Incidentally, I have no idea why Ton renamed the IoR parameter “Refr”, because it just causes confusion.)
they both would have
To see the rendering result at 1:1 ratio (100%)…
Render at the resolution you want. Save the image F3. Open it with a Viewing app (like Irphan View). It should display ok.
Alexandre Rangel
It’s the same effest that happens when IE (or any other app) does a rescale of a picture to make it fit the screen.