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.

Lesson 5 and Lesson 6

5. Introducing Layers

In this lesson, I am introduced to layers, Firstly, the easier way to convert a flat background into an individual layer just my clicking on the lock icon on the right-hand side of the layers panel to turn it off. I found out that the layer above with affect all the layers below it and that it's possible to customize the checkerboard pattern by going to the edit menu, then drop down to Preference and choose Transparency and Gamut. One can use the Channel Mixer Adjustment Layer to temporarily turn an image black and white and use the Brightness Contrast Adjustment Layer to turn an image into near silhouette. 

At the brush tool and painting area, I learned about the Hardness value which changes how the edge of the brush stroke look (to look soft or sharp and crisp) and also the Spacing value which affects the continuity and smoothness of the brushstroke. I also learned a new trick of painting straight line by clicking at one point, and then shift + clicking at another. 

It's possible to distinguish black from non-black pixels in an image by using the threshold adjustment layer. Luminance levels are measured from 0 to 255. 0 is black, and then 255 is white and the threshold adjustment layer works in the way whereby anything brighter than a certain value is going to turn to white, and anything darker than a certain value is going to turn to black.

This lesson also demonstrates how to use the crop tool to expand the canvas to make room for a new canvas and fill in any unwanted areas of transparency with a new flat background. Next, was the clipping mask and the layer mask. The clipping mask allows one to clip an adjustment layer so that it affects just the crane layer rather than all layers below it. While the layer mask allows one to hide portions of a layer that are not selected and show the portions of the layer that are selected.

Lastly, to fill a selection with color while deleting the selection at the same time, press Alt+Backspace to fill the selection with the foreground color, press Control+Backspace to fill the selection with the background color and press Shift+Backspace to bring up the Fill dialog box. In order to add a non-adjacent layer to the selection, just click on one layer, then go to another layer, press the Control key and click on the empty portion of the layer but not the thumbnail. That's all for Lesson 5.

6. Saving Your Progress

Firstly, I didn't know that photoshop has an auto-saving setting which I can adjust to how often I want the program to save my work. It also a good thing to note that history is not saved together with the image file inside photoshop so one have to be extra careful and assured when abandoning unsaved changes. 

When saving as a PSD file, the As a Copy sign should be turned off and Alpha Channels, Layers, Notes, and Spot Colors should be turned on. When one turn on Maximize Compatibility, the file size will grow significantly as it is saving a flat version of the file along with a layer version. 

TIFF is is the most widely used file format for print images and that's because it's widely compatible and it features lossless compression. One can save a layered image as a TIFF file but it's recommended not to do so as it will increase the file size and most of the time people don't expect seeing layers in TIFF file. This is because when sending an image for a print, one generally wants the file size to be as small as possible.Thus when saving as a TIFF file, Alpha Channels and As a Copy can be turned on and Layers can be turned off. LZW, the lossless compression scheme can be turned on as it doesn't hurt the image unlike lossy compression as is associated with JPEG, is sometimes bad, but not always.

As for the PNG format, which is popular in the world of design, like TIFF, supports full-color images as well as lossless compression.However, it doesn't support layers but does support transparency. Thus, when saving as a PNG file As a Copy will definitely be turned on. Set the compression to smallest/slow and interlace to none otherwise, the file's going to load oddly inside of a web browser.

Lastly for JPEG format which is ideally suited to archiving continuous tone digital photographs. It neither supports layers nor transparency and always relies on lossy compression, meaning that it has to rewrite the colors of pixels when it saves its files. Hence, in return, we will get smaller file size. When saving as a JPEG format it's recommended to set the quality setting to the absolute maximum. For the format options, Baseline Optimized will be a better choice as it applies lossless compression, which generally helps to get the file size ever so slightly smaller, and these days everything that supports JPEGs supports Baseline Optimized.

Lesson 3 and Lesson 4

3. Image Size and Resolution

In this lesson, I am introduced to the basic building units of a raster graphic, the pixels. Pixels is the square unit of color. An image size is determined by the number of pixels in an image while the resolution of an image is determined by the number of pixels that are packed in a square inch when you print that image. It interesting to know that the resolution value applies to print only and it's actually meaningless on screen.I find out that "dpi" actually stands for "dots per inch ", a measurement of how much detailed color information a raster image contains.

I understand how image size is calculated and before this I actually did not know that to calculate an image size one have to take into account the RGB pixels. For printing, the image should at least have 300 dpi (CMYK) which is an industry standard for fine resolution images while for the web, 72 dpi (RGB) is enough. I can change the resolution value of an image by upsampling or downsampling it. However, if I do not want to change the number of pixels but only the resolution value I can turn off the resample image check box. However, at such I will change the width and height value of the image.When resampling an image, there will be interpolation whereby Photoshop rewrites every single pixel in the image. Thus, both upsampling and downsampling is technically a destructive modification. 

There are 6 interpolation settings. They are the nearest neighbour, bilinear, bicubic, bicubic smoother, bicubic sharper and preserve details respectively. The automatic setting when downsampling is the same as bicubic sharper while when upsampling, the automatic setting is the same as preserve details. After this lesson, I understand how to change the interpolation setting to the one that is the best to preserve the quality of an image when resampling an image.

4. Crop and Straighten

This lesson is pretty straightforward and easy. I know how to crop and straighten the image already. The lesson recommended us to use the ruler tool when straightening an image so that we can modify the line as much as we want before straightening. At such, the image will be straightened more accurately. I learned that when I rotate the image as I crop it, I will actually resample the image. I have not come across the perspective crop tool before hence it's vital to learn how it works.  I am amazed by the content-aware crop which can help to fill in missing background details while cropping an image.