The first image is that of an old brick built tower. I chose this image as I know that bricks look great under an increase in contrast, they seem to make the building stand out by defining each stone as an individual unit, rather than a bland brick wall.
The first colour image is by no means a fair representation but the brickworks colour has intensified so much that it really does look burnt in. Having the cloudy sky in the background has added to the contrasting effect. Inevitably there will be shadow clipping in the bottom of the image, but for this type of image I think it works well.
When converted to black and white the contrasts seem more balanced and authentic, again the brickwork looks great making the building look more foreboding, older and eerier. I prefer this version. All adjustments were completed in Photoshop using a curves layer with a heavy 'S' Curve, and another Channel Mixer layer to convert to black and white, with some minor adjustments to the levels of RGB.
The second image was taken last summer of Southwold Peer. This image was taken late in the year, around October November on a sunny day. The original image was well balanced but by increasing the highlights (giving it a high key effect) it has given the image of a feeling in summer on a bright hazy day.
I am not sure which version I prefer, but I think I am leaning towards the colour image, the black and white looks as if it really needs a boost in contrast, whereas the colour version looks more acceptable. This was an interesting exercise and although I boost the contrast in many of my images, especially for B&W versions, I have never given, or thought to give any image the high key treatment.
I suspect that portrait images of a small child or a woman would also benefit from this as it really does soften the image as well.