Hi group.
I would like some feedback on an effect that I have noticed on some occasions when looking at images taken with my Alpha 100.

The effect was first noticed when looking at some bright fireworks shots. Many of the firework effects seemed rather "square and chunky" when compared to dimmer or less intense lights. This effect is seen at 100% scale.

Many distant streetlights (red, green, sodium vapour) also have a square blocky look when viewed at 100% scale. Lights that should apear round will have square corners, or square halo around them. Light through tree leaves can have the same effect, more chunky and square than expected. Although other shots through the same type of foilage or city lights can look perfectly norma.
I only shoot using the RAW mode, which does not use any image processing (D-range, is not used).

I have been using a Canon A620 7.1 MP camera up until now. I would have to say that this effect was not noticed with this camera (to the same degree). The A620 is NOT a DSLR, but it does take some extremely good shots.

Is this a normal effect (seen with other DSLR's) or does the camera/software have an issue with pixelation? As the A100 is the only DSLR I own, I cannot easily test this.