HDR (High Density Range) in Photoshop

September 15, 2011

HDR (High Density Range) in Photoshop

     HDR or High Density Range is a term that describes an image scene that has a huge difference between the brightest areas (highlights) and the darkest areas (shadows). I'm going to be using an interior architecture scene for this instalment.

        In this digital era, in my opinion there are pros and cons to using software. The key problem that many people have or clients looking for a "cheap way out" is to reply on the technology to replace excellent photography and lighting skills. For this instalment, I'm going to use HDR to try and be able to keep detail in the highlights, while, at the same time "bringing up" detail in the shadows. Normally, the best way would be simply to use additional "hot lights" whose colour temperatures are 3200 degrees Kelvin. You could also use small battery-operatred flash heads, and add a warm-toned filter (e.g. 85) to change the "colour" to 3200 degrees Kelvin, from 5500 degrees Kelvin (Daylight).

A Nice Buffet Room from a Hotel in  Hawaii

 I exposed "normally". However, I already knew that the extremes (highlights and shadows) would not record well. The detail in the  shadows on the left are "lost", meaning that they just did not record on the CCD's of the DSLR. The highlights also were overexposed. The candle-shaped lightbulbs in the fixture are stars, and there are some hot spots on the ceiling.THose latter "hotspots" would be corrected in Photoshop with the "rubber stamp".

Notice the Blurred People in the Photo

     Normally, for a contract, I would have had the assistance of the staff, and the area would have been cordoned off. However, I only got the permission to shoot, as I was on vacation, and wasn't looking for work, nor was the hotel looking for photography. Notice the 2 people at either end of the dotted-line.

HDR will help to remove them.

     When you shoot for HDR, you need to use a tripod, and keep the f-stop the same for all of the images. The reason for this is that HDR takes many photos (Starting with at least 3), and tries to takes the areas with adequate detail. It then mathematically combines these choice exposures) into 1 image.

This is the image that HDR generated.

To the right of the photo is a menu that allows you to improve upon what HDR has done.

This is the image that I adjusted with the menu parts on the right side.

At the bottom of the Photoshop large window are the 3 images that I started working with.

The original image with the 2 people

The HDR image with the 2 people almost removed

There are a few other details to notice.

1. Notice that the man in the left background has disappeared.

2. The dishes in the lower right foreground are receiving daylight and hence are bluish in colour.

I had set my camera white balance for a warm-tone (3200 degrees Kelvin).

I used the magnetic lasso command in Photoshop to Capture the area needing to be whitened 

(blue removed)

I used a warming filter to whiten the dishes, 

as well as using the density "slider" to whiten the dishes better.

I used a filter command in Photoshop to whiten the dishes.

2. The dishes in the lower right foreground are receiving daylight and hence are bluish in colour.

I had set my camera white balance for a warm-tone (3200 degrees Kelvin).

I used the levels menu to add more mid-tone detail (lighten up).
The result is below.

This is "almost"the final image.

The left side shadow detail has unfortunately been almost lost, and the ceiling "hot spots" will need to be retouched out with the rubber stamp.

Today's Photographic Terminology

CCD: An acronym for something called a "charged Coupled Diode". These are microscope-sized sensors that have replaced film and "capture" the light and detail of a scene.

Detail Loss:  Photographic information that did not record on the CCD's of your DSLR.

DSLR: Digital Single Lens Reflex or a digital camera with removable lenses and a built-in mirror for you to see the image when holding the camera.

HDR:  An acronym for High Dynamic Range. This simply means that there is a big difference between the darkest area and the lightest areas of a photo. The opposite might be of a white cat on a white sofa with very soft and diffused lighting.

Highlight: The light areas of a photo.

Kelvin Colour Temperature Scale:  Like a thermometer (heat and cold scale), this scale measures the temperature. What Kelvin basically did was heat up an object that did not change colour when heated. Fireworks are made form metals that when heated give off colour. (Magnesium is white, iron is red, sulphur is yellow and so forth).  The hotter the temperature, the "colder" the colour of the "neutral metal was). So on the Kelvin scale, reds, yellows and oranges are low in value (800-3800 degrees Kelvin), while the cold-appearning colours are hot in colour (4000-11,000 degrees Kelvin). This does sound "strange". However, imagine if you've ever seen an acetylene torth. It has the gas, and oxygen. Without oxygen the flame burns warm (reddish-orange). Adding oxygen changes the flame colour to almost a whitish-blue that burns high on the temperature scale.

Shadow: The dark area or areas of a photo.

Warming Filter: A term from the film era, which now is a software menu. A warming filter adds red, yellow or orange colour to eliminate blues, cyans, and greens from a photo that was taken without setting the white-balance of the camera.

White Balance: a software menu on your digital camera that matches the nature of the colour temperature     in a photographic scene with the camera