Lesson 7 & Lesson 8

7. Brightness and Contrast

In this lesson, we are firstly introduced to the core concept of luminance inside of a digital image. A digital image is made out of multiple grayscale images. Every one of those gray scale images has luminance levels that go as dark as black and as bright as white and has different gray values in-between. The darkest of the luminance levels are known as the shadows while the brightest luminance levels are known as the highlights. Everything in-between is known as the mid tones. Gray scale images are known as channels and they contain 3 channels. The Red channel, Green channel and Blue channel. 

There are 3 auto commands. Auto Contrast simply darkens the darkest pixels to pure black, lightens the lightest pixels to pure white, and redistributes all the other tonal values in between. Auto Tone does the same same as Auto Contrast but it does on a channel-by-channel basis, meaning that the Red, Green and Blue channels each receive their own separate boost in contrast. Hence, Auto Tone changes the colors in the image. Auto Color is similar to Auto Tone. It also darkens the darkest pixels to black and lightens the lightest pixels to white on a channel-by-channel basis. But Auto Color goes a step further. Rather than simply redistributing all the other tonal values in between, it tries to correct any unwanted color cast by neutralizing the mid-tones in the image. I didn't know that the Brightness and Contrast setting also has an auto function.

I also learned that it's possible to apply a dynamic adjustment layer to an image. At such, instead of having permanent modifications to the image, temporary modifications are applied. Just have to go up to the layer menu and choose New Adjustment Layer. 

There are two blend modes that are generally more useful. One is Multiply, which will allow you to darken the image. The other one is Screen, which does the opposite of Multiply. The most useful one in the contrast mode is Overlay, which will increase the contrast of an image.

This lesson also taught us how to read the histogram and put in into use. A histogram of a good image should have a gradual incline in the Shadow region and then a bunch of mountainous activity in the Midtones, and then finally a gradual decline into White.

Lastly, I learned how to use the Shadows/Highlights command to correct an image that has too much contrast. It's also good to note that Shadows/Highlights is not available as an adjustment layer in Photoshop.

8. Balancing Colors

This lesson is pretty interesting. Firstly, we learned how to identify the color cast of an image by using the eyedropper tool. With the eyedropper tool, click on something that ought to be either white or gray color in the image then the identified color will be shown inside the color panel. Hue is the actual color. Saturation value is perhaps the best indicator of the color cast of an image. It tells us how intense is the color cast is. It's good if the neutral element inside the image has a very low saturation value of 3% or below. To adjust the color cast manually, one can use the Color balance adjustment layer and adjust accordingly to one's subjective decisions. Turning the Preserve Luminosity checkbox on will brighten the image up slightly. Another way of correcting color cast is by applying photo filter. 

The easiest method for color balancing images is by using the camera raw filter. First go up to the Filter menu and choose the Camera Raw Filter. Then use the eyedropper which is known as the White Balance Tool at the horizontal toolbar at the top of the screen to click on the neutral part of the image in order to correct the color cast. However, it's a permanent so-called destructive modification because Photoshop has rewritten all the pixels inside the image. While the adjustment layers, will still allow editing to the modifications.

When adjusting color intensity with the Vibrance adjustment layer, the saturation slider will increase the saturation of all the colors inside the image while the Vibrance slider saturate colors according to one's needs. Vibrance increases the intensity of the more muted colors and leaves the already well-saturated colors alone. 

For the Hue/Saturation adjustment layer, I didn't know about Targeted Adjustment tool. One can drag the Targeted Adjustment tool to change the saturation of a color selected. Press the Control key or the Command key on the Mac and drag to change the hues of the selected color. Hue/Saturation can create a sepia-tone effect just by turning the Colorize checkbox on and adjusting the hue and saturarion accordingly.