Monday, May 10, 2010

How Many Colors Does It Take? Adobe Photoshop CS5s HDR Toning Lets You Decide.

Probably the most famous song from the Broadway play “Rent” is “Seasons of Love”. One of the lines counts the number of minutes in a year. (It’s 25,600) That actually doesn’t come close to the number of colors available to people playing with HDR (High Dynamic Range) photography. The typical HDR image is rendered out as a 32 bit image and gets knocked down to either 16 bit or 8 bit for printing. When we start out with the 32 bit color the theoretical numbers of colors available is about 4.2 billion distinct colors. It’s a little overkill. But, the place where it seems all of the 32 bit color range is on display is in the Caribbean. Today’s image is of the cruise ship harbor in Antigua. One of the coolest things about Antigua is the fact that the cruise ships drive right up into town. If we could pan today’s image about fifteen degrees to the right we’d see the tip of the cruise ship in port for the day. The town of St John goes up the hill from the wharf and is one of the nicest towns in the Caribbean. Today’s image is another combination image where the sky is straight and the foreground has been toned (today, quite extensively). You can “get away with it” on shots of many of the Caribbean locations because of the bright colors used to paint the buildings. There is bright red, and bright blue, and bright yellow, and green and just about any vibrant color you can imagine. It find out more about the how of today’s image, hit the “read more”.

Today’s image was just about having fun. First thing to be done was to make a mask to separate the sky from the foreground. I guess I just haven’t accepted the ease of using the Refine Mask feature of Photoshop CS5 yet, because I fell back into using the Calculations dialog box found in Image/Calculations. After running through several iterations of possible combinations I came close by combining the Blue Channel with the Red Channel using Hard Light as the Blend Mode. One of the nice things about the Calculations dialog is that it gives you a new Channel. Once I had the first pass I went for another round and came up with a pretty clean mask. A little checking and fixing a few stray pixels and the mask was done.

With the mask complete and out of the way I took another copy of the shot and set up for the dense clouds that are actually in the original shot. With the clouds looking menacing in the second copy of the shot I just pulled the number two shot over into the number one shot (the one with the mask already set up). For the next step all that was required was applying the Channel to a new Layer Mask and the basic image was there.

In going through the “normal” Hue/Saturation Adjustment Layer sequence of saturating each color (Red, Yellow, Green, Cyan, Blue, and Magenta), the only thing considered was how the saturation effected the foreground. If saturating a color had too much influence on the sky, the same Layer Mask was used in place of the Mask that came along with the Hue/Saturation Adjustment Layer, keeping the sky reasonably “normal”.

With the sharpening Layer (using a High Pass Filter sharpening) the same Layer Mask was employed to prevent the clouds for being sharpened. Clouds are soft, puffy things and I tend to keep them that way. I don’t typically see any point to sharpening clouds.

I vignette using an unsharpened copy of the final image is applied with the center knocked out using the Rectangular Marquee Tool with the feather set to about 133% of the Resolution setting. In the case of most of my images that would be a 200 pixel feather, based on a full size Resolution of 150 PPI.