Firstly, we'll take the original image.
Notice the washed out colour, dark shadows and lack of any real contrast.

To fix this, we'll adjust the brightness, contrast and up the saturation to give the image more vibrancy and depth.

OK, now it looks much better, but still not quite there.

The next step is to define the levels of the image (whites, blacks and midtones).

This will give more contrast in the the tonal values of the image and allow you to specify what should be a true white, black and midtone.

Notice how the whites are now much whiter than before instead of a washed-out yellow tinge.

Finally, we're going to use the Curves tool with the intention to brighten up the raspberries. They're still quite dark and undefined.

The Curves tool allows you to selectively alter the tonal range of a colour. This works well for our raspberries as we only want to alter the red colours within, not the entire image.

Using the eyedropper tool in Photoshop over the desired part of the image will show you where that colour range sits within the Curves chart.

We found our range and ramped the reds up to brighten the berries. Great!

The final piece