What is RAW?

RAW isn't really a file format so much as it is category of similar file formats. Each camera manufacturer has their own version, due in part to differences in sensor technologies but also in an attempt to achieve competitive advantage.

A raw file stores the data exactly as it comes off the sensor. For most cameras, this is a single channel of pixels in what is known as a Bayer mosaic. Every pixel only senses a single color and these are then arranged in a checkerboard pattern. Every other row consists of alternating blue and green pixels, with the rows in between composed of alternating green and red pixels. Thus, half of the total pixels will be green with one quarter each of red and blue. This may sound odd at first, but since human vision is more sensitive to green than the other two colors, it actually works.

The raw data is called "raw" since it is totally unprocessed. At this point, white balance and other adjustments have not been made and the data is still an exact recording of what each photosite recorded. One photosite makes one pixel. Enough pixels and you have a raw image. It won't look like much until it gets processed into a visible image, a process that happens whenever you open a raw file in Photoshop Adobe Camera Raw, Nikon Capture or other raw file converter.

Raw files contain the absolute maximum amount of data possible, giving you tremendous power to post-process them to maximize your creative efforts. This makes them ideal to archive as "digital negatives" but does mean that you have to process every file at least to some extent before it can be used as an actual image.

Here I will explain you how to do adjusting process.

1. Specify White Balance

The White Balance setting controls the overall color of image, making it appear cool (blue-green), warm (yellow-red), or neutral (no color bias). There are three ways to adjust the White Balance: use the pop-up menu; move the Temperature and Tint sliders; or use the Eyedropper in the upper left of the dialog box. All three methods accomplish the same thing; they just have different ways of changing the Temperature and Tint sliders.

If the image has an area that should obviously not contain any color (white, black, or gray), choose the Eyedropper tool and click around in that "no-color" area. That causes Photoshop to calculate the proper Temperature and Tint settings which will render that area neutral (we prefer to use white balance cards). If you don't have such an area, cycle through the choices that are available in the White Balance pop-up menu until you find the one that delivers the most pleasing result and then fine-tune the adjustment by moving the Temperature and tint sliders.

2. Adjust Highlights

The Exposure slider determines how bright the brightest area of your image will be. At a certain point, you'll end up making the image so bright that you'll start to lose detail in the highlights. You can tell when this is happening by turning on the Highlights checkbox at the top of the Camera Raw dialog box. That will cause any areas that are losing detail to be highlighted in red.

Behind the scenes, your image is made out of red, green, and blue light. The red highlighting doesn't differentiate between losing detail in one, two, or all three of the colors that make up your image. To see a more accurate view of what's happening in the highlights (known as a clipping display), hold the Option/ Alt key while moving the Exposure slider. Areas that appear white contain no detail whatsoever (they're solid white), while areas that appear in color indicate that you're losing detail in one or two of the colors that make up your image (known as clipping) and have not become solid white yet.

We suggest that you adjust your image while the Highlight checkbox is turned on so you can see when you start to lose detail, and then use the clipping display to make sure that the only areas that become solid white are Specular Highlights.

TIP: Specular Highlights.
Specular highlights are defined as the bright areas in your image that are caused by direct reflections of light on shiny objects, or when the light source is visible in the image. It's fine for these to be reproduced as solid white.

CAUTION: Watch the Histogram.
If you don't want to use the clipping display, keep an eye on the histogram at the top of the Camera Raw dialog box. A spike on the right edge of the bar chart indicates a loss of highlight detail. If the spike is in color, detail has been lost in one or two of the colors that make up your image. When the spike turns white, you've lost detail in all three colors, which means the brightest area of your image is solid white.

3. Adjust Shadows

The Shadows slider determines how dark the darkest areas of your image will be. Turning on the Shadows checkbox will cause any areas of the image that are losing detail to be highlighted in blue. As with the Exposure slider, you can hold Option/ Alt to see if those highlighted areas have become solid black. We usually adjust this slider until a tiny speck of the image becomes solid black.

4. Adjust Remaining Sliders

After adjusting both ends of the tonal range, it's time to fine-tune the overall look of your image by using the Brightness, Contrast, and Saturation sliders.

The Brightness slider will change the overall brightness of the midtones of your image. Move the slider until the result is to your liking A. Now we're ready for the Contrast slider. Moving this slider to the right will add some "pop" to your image by increasing its midtone contrast B. Finally, adjust the Saturation slider to control how colorful your image will be. Most images will benefit from a boost in saturation by moving the slider to the right of center c.

This is a sample of the changes done in a RAW file.  The left image is the RAW file as shot, the right side image is with highlights, shadows, contrast and saturation adjustment. 

Next tutorial I will discuss the setting for the Detail Tab, Lens Adjustment, cropping, straighten, synchronizing and others.

Orginal Raw File

Adjusted Raw File