300d (Digital Rebel) vs 600d (Rebel T3i): Older one much more faithful to real life

hestan wrote:

You have a definitely valid point, and by no means, I can claim that my monitor is good or perfectly calibrated.

But on the other hand, I have viewed the two pictures on a number of different displays and the 300D one always looks better, no matter what.

How do they compare on your monitors?

Well, how should I be able to tell which one is better (unless I had a color calibrated color chart in the image itself)? Both look fine, no egregious color shifts.

Obviously, when inspecting the RGB values of the two images, the two images are not the same, they have a different curve applied, i.e. the 300D has more contrast, the house on the left is darker, while the sky is more blown out, whereas the 600D, the sky is not as blown, while the trees and the house are brighter.

Some of it could be the settings (picture style, AOL), some can be the different sensors, some can be slight difference in adjustment of the camera.

A sensor actually has to have the ISO calibrated, the different ISO are simulated by applying a gain to the signal amplifier. A specific gain has to be set to make the sensor equivalent to ISO 100, for example. So, there may also be slight variations in this settings between different cameras (some review sites test this, or did test for this in the past). If the two sensors do not expose exactly the same, it's actually difficult to compare the output. Ideally, a particular homogenous grey wall should be, e.g., 128, 128, 128 (RGB) with two different cameras, but rarely is. Without calibration, everything is subjective, so you just choose settings that suit you.

It is a good idea to print them for further comparison.