Archive for the ‘Digital Photography’ Category

Setting Black and White Points

October 14, 2011

Do you want to make this….

RAW capture

Look like this….

Post-processed using Adobe Raw Converter and Photoshop CS3

Or make this….

Original RAW capture

Look like this….

Arches National Park, Utah, converted with ACR and PS CS3

Click for Larger Images

Since some people have asked me how I post-process images,  I’ll attempt to sporadically post some of my basic workflow steps that I use when processing my images in Photoshop. I always capture in *RAW format (rather than Jpeg)

The above image of a juvenile Cooper’s Hawk eating a pigeon was made at a local boatramp. The bird allowed a close approach and I managed to get quite a few images. As you can see the original is all washed out. This is because I exposed “to the right”, which basically means that I try to get my histogram on the back of the camera to have most of the “peaks and valleys” to the right of middle (the highlight end) of the histogram without overexposing the whites (i.e no flashing “blinkies” in the LCD).  Most of the tonal detail resides in the right 2/3 of the histogram and exposing to the right ensures that you capture as much tonal information as possible as well as reducing digital noise. There is less tonal information in the left (shadow) side and that is also where most digital noise is likely to manifest itself.  Anyway, since this image has a lot of highlight tones and not a lot of dark tones, the original RAW capture looks rather washed out. But, since I have captured most of the tonal details by exposing to the right, I know I can add in the contrast when I process the RAW file.

The scenery images where made at Arches National Park, Utah. I wish I would have had more time..awesome scenery!

Before Starting
It helps if your monitor is calibrated so that your brightness/contrast are accurate so that you have a solid foundation to start with.
Check this site out first to help:
http://w4zt.com/screen/

To create a grayscale stopwedge in Photoshop:
http://www.ohio.edu/people/schneidw/digital/step_scale.html

There are free basic calibration tools on the web tthat will get you in the ballpark, but if you are serious then you can purchase a piece of hardware/software such as a Spyder: http://spyder.datacolor.com/

This essential attaches to your screen and calculates the right calibration based off these screen measurements. Since I don’t have one, I use Adobe Gamma and that basically runs through a wizard-type set-up to adjust my monitor.  It’s not as accurate, but I have seen many of my images printed in magazines that look comparable to how they appeared on my monitor, so I am happy.

Tip#1 – set black and white points

To adjust the image for contrast and eliminate color shifts/casts we want to set the darkest and lightest parts of the image. We want the shadows to be dark enough without being muddy and the whites to be bright without being burnt out. Once we set the black and white points, the mid-tones will fall into place automatically.

RGB values of 0, 0, 0 equal true black and 255, 255, 255 equal true white. By setting the darkest pixels in the image to R=10, G=10, B=10 you retain shadow detail. Setting the lightest pixels to 245,245,245 will retain detail in the whites. Since RGB values dictate color in our images, setting each of these color channels to the same value will neutralize unwanted casts in your image.

1. Open your image in Photoshop (File > Open…).

2. Add a Levels adjustment layer by clicking the Create Adjustment Layer icon (the split circle at the bottom of the layers palette) and selecting Levels.

3.Double-click the Black Eyedropper and set the RGB values to 10,10,10. Press OK.

4. Double-click the White Eyedropper and set the RGB values to 245,245,245. Press OK.

5. Select the Black Eyedropper tool, hold down the Opt (PC-Alt) key and move the Black slider to find the darkest pixels in the image.

6. Click the darkest point in the image with the Black Eyedropper tool. It is now set to 10,10,10.

7 .Repeat the process while holding the Opt (PC-Alt) key and moving the White slider to find the lightest pixels. Avoid specular highlights. Click the lightest pixels with the White Eyedropper. White is now set to 245,245,245. Click OK.

If you have any questions, or are interested in learning how to improve your digital images, I can be available for one-on-one instruction. Contact me for  at: jrhough1@snet.net

*RAW vs JPEG

Although I shoot in RAW, many people shoot jpegs since the images saved to the memory card are smaller and allow you to capture more images per card than with shooting RAW. There are plenty of sites that discuss the pros and cons of each, but for me, RAW is the way I shoot since I feel I have a lot of latitude when processing images that jpegs do not give me.

The following steps assume you are using jpegs straight from the camera. Once these native jpegs are downloaded to your computer and a file is opened in photoshop, immediately do a “Save As” and change the file format to either .TIFF or .PSD (essentially the same). This ensures that your original jpeg remains intact as your untouched digital ‘negative’. Another reason to make the conversion is that jpeg format uses lossy-compression (which basically means that it loses information when its compressed or saved) which allows jpegs to achieve their small file sizes compared to .TIFFS or PSD files. Each time you open a jpeg file, make changes and then resave it, you essentially are dumping information from the file. Will it be perceptible to you on a monitor or on a print?..perhaps not in many cases, but why not maintain the integrity if at all possible?

Advertisements