i am working on this scene as shown in the attached picture, after i rendered it the colors became darker than what it appears in Blender, when i opened it on photoshop to give it a little brightness, the right three bottles become lighter than the left one, can any one help me please if there is any mistake in my scene. . thanks in advance.
We can see a gradient of light:
It goes from dark to light, which is not surprising at all keeping in mind how the scene is lit. The explanation is very simple: you have an area light on one side, but not the other. The further away an object is from a light source the less light reaches it. Sun lamps in Blender are different from real world lights because they simulate a light source infinitely far away, but the other types of lamps in Blender will become dimmer as you go further away from them. You will just need to adjust your lighting until you get your desired result.