1. 1 Introduction to Computer Graphics – CGS-1586C Spring Quarter 2011 Instructor: Amanda Dickinson Tues/Thurs from 6:00PM to 7:50 PM

2. 2 Overview for Today  Wikispaces  Make-up Essay Due  Adjusting Images  Layer Blend Modes  In-Classroom Project  Homework

3. 3 Wikispaces  If you haven’t written down the wikispace link, here it is again.  Project details, weekly power points, and exercises that you need to complete will be on the wiki.  http://cgs1586c.wikispaces.com/ Now you can’t use the excuse “I missed that day’s work.” Haha!

4. 4 Make-up Essay due today.  For those that needed to do the make-up essay, please hand it in to me if you haven’t already.

5. 5 Adjusting Images  We’re going to experiment with all the other stuff found in the Image menu today.  My Photoshop version is CS4, so there may be some slight differences, so bear with me.  Use Photoshop to open up one of the stock images you brought to class today  If you didn’t bring one, I have some stock images in the Week 6 Course Files

6. 6 Adjusting Images We already went over some of these, now it’s time to see what the rest of these tools do.

7. 7 Adjusting Images These are the Image modes. Clicking on these will change your image value properties from greyscale, a type of color mode, or even bit values. Try changing your color mode to greyscale. What happens? Remember to undo any changes after applying color modes. We want our picture in it’s default color mode for the next exercises.

8. 8 Adjusting Images We already looked at levels and curves in this section. Let’s experiment with the other tools to get a feel for what they do.

9. 9 Adjusting Images  All these tools will alter the color, contrast, or color saturation of the image in some form or another. It’s up to you on what tools you prefer to use for your projects.  Let’s start by clicking on shadows/highlights.  Make sure the preview checkbox is selected.  Move the sliders back and forth. What happens to the image?  Press CANCEL when finished, as we don’t want to alter the original image just yet.

10. 10 Adjusting Images  Now, let’s click on variations.  This tool is used for color correcting your photos. (Like say your photo has too much yellow tint)  The original is your original photo, the current pick is what your photo will look like after your changes.  Shadows, midtones, etc will focus on changing the specified value range in your photo, midtones is default.

11. 11 Adjusting Images Notice how the color picks revolve around your current pick image like a color wheel. The color images directly across from each other are complimentary and will cancel each other out. More blue will correct yellowish images. More red will correct cyan images. Etc.

12. 12 Adjusting Images  Clicking these images will make your image lighter or darker, obviously.  Press cancel when finished messing around, as we don’t want to alter the image just yet.

13. 13 Adjusting Images The rest of the image adjustments can be done using the image adjustment mask tool found on the layer pallete. Let’s start by clicking Brightness/Contrast. Brightness will adjust how washed out or dark your picture will be. Contrast will change the contrast of light and dark values. The higher the number, the more contrast there is.

14. 14 Adjusting Images Right click on the adjustment layer and select delete layer to delete it. Make a new adjustment layer using Exposure. This tool will be somewhat familiar to you if you ever tried photography. By adjusting the sliders you can make a picture darker or more washed out. Once finished experimenting, delete the adjustment layer.

15. 15 Adjusting Images Click on Vibrance. This tool will adjust how much color saturation is in your picture as well as how bright the colors are. By dragging the sliders all the way to the left, note how your picture becomes greyscale. Like before, delete this layer.

16. 16 Adjusting Images Click on Hue/Saturation. This is one of my favorite tools. This tool will change the color of your image, similar to how the Variations tool did it. It also has a slider to change the saturation and lightness of your image. Clicking the colorize box e can change a your image to a monochromatic color of your choice. This works with greyscale images, too. Once done experimenting, delete this layer.

17. 17 Adjusting Images Black and white is a very interesting tool. It will change your image to greyscale, but using the hue sliders you can adjust the grey values from specific parts of your image. Clicking the Tint box is similar to the colorize box from hue/saturation. Again, delete the layer when done experimenting.

18. 18 Adjusting Images Click on Photo Filter. This tool will use a particular color tint or a pre-made color filter over your image. Adding an orange filter will give your picture an orange tint to it, and so on. Use the density slider to adjust how much color filters into your picture. Delete the layer when finished experimenting.

19. 19 Adjusting Images Click on channel mixer. This tool is commonly used to make images greyscale except for a certain part. Click the monochrome checkbox. Make sure the channel mixer layer is selected and grab your paintbrush. Make sure the foreground color is black. Paint over an object on your picture.

20. 20 Adjusting Images  If you notice in the layers, the adjustment mask has a second thumbnail that’s white. The white represents what is being altered by the mask.  If you paint black in the mask, the black will represent the parts of the photo not being affected by the mask.  Shades of grey will also work, the darker the shade the smaller the effect of the mask.

21. 21 Adjusting Images After a bit of brushing around, you can use color channels to do cool stuff like this! Delete or hide this layer when finished. Original ->

22. 22 Adjusting Images Now for the last section. Invert will take your colors and invert them. Black will become white, green will become pink, etc.

23. 23 Adjusting Images The Posterize command lets you specify the number of tonal levels (or brightness values) for each channel in an image and then maps pixels to the closest matching level. For example, choosing two tonal levels in an RGB image gives six colors, two for red, two for green, and two for blue. This command is useful for creating special effects, such as large, flat areas in a photograph. Its effects are most evident when you reduce the number of gray levels in a grayscale image. But it also produces interesting effects in color images.

24. 24 Adjusting Images The Threshold command converts grayscale or color images to high-contrast, black-and-white images. You can specify a certain level as a threshold. All pixels lighter than the threshold are converted to white; all pixels darker are converted to black. The Threshold command is useful for determining the lightest and darkest areas of an image.

25. 25 Adjusting Images The Gradient Map adjustment maps the equivalent grayscale range of an image to the colors of a specified gradient fill. If you specify a two ‑ color gradient fill, for example, shadows in the image are mapped to one of the endpoint colors of the gradient fill, highlights are mapped to the other endpoint color, and midtones are mapped to the gradations in between.

26. 26 Adjusting Images Selective color correction is a technique used by high-end scanners and separation programs to change the amount of process colors in each of the primary color components in an image. You can modify the amount of a process color in any primary color selectively—without affecting the other primary colors. For example, you can use selective color correction to dramatically decrease the cyan in the green component of an image while leaving the cyan in the blue component unaltered. Relative changes the existing amount of cyan, magenta, yellow, or black by its percentage of the total. Absolute adjusts the color in absolute values. This is an advanced tool, we probably won’t need to use this.

27. 27 Layer Blend Modes  Layer blends? What? Layer blend modes give us different ways for layers to interact (or blend) with other layers below it. Without this tool, we’d have to just rely on transparency to blend layers together. Once you learn the gist of the blend modes, you will never be able to live without them. Let’s go over the basics of blend modes then try to make something cool with them.

28. 28 Layer Blend Modes  You find your layer blend modes in the layer pallete in a drop down menu.

29. 29 Layer Blend Modes  Photoshop groups up the layer blend modes for easier selection.  Normal blend mode is the default.  Dissolve is rather useless, we won’t need to bother with it.  The important ones are darken, lighten, comparative, and composite modes.

30. 30 Layer Blend Modes  These blend modes can seem a bit overwhelming at first.  All you need to know is there are some modes that darken the image some that lighten the image some that boost contrast some that compare pixels between layers and some that affect the color/luminosity of an image  The best way to learn how they work is to simply experiment with them.

31. 31 In-Classroom Project  We are going to use some of the tools we learned in Photoshop so far to create something from an original photo:  To this: Black and WhiteMonochromaticAnalogousComplimentary

32. 32 In-Classroom Project  We are going to take the original photo and Change it to pure black and white Make a monochromatic image Make an analogous image Make a complimentary color image  Don’t worry, this is easier than it looks.

33. 33 In-Classroom Project  Open up one of your stock photos into Photoshop (if you don’t have one, use one of mine provided)  Save this file as lastname_firstname_layers01.psd  First, we will make our photo pure black and white Make a new layer adjustment mask, click Threshold Adjust the threshold bar till you are satisfied with it

34. 34 In-Classroom Project  Go to file > save for web and devices  Use the JPEG High preset in the preset dropdown menu  Save this file as lastname_firstname_layerbw01.jpg  Our first picture is done!

35. 35 In Classroom Project

36. 36 In-Classroom Project  Now make a new layer on the layer pallete. Name it “Color1” by double clicking the layer name  Fill this layer color with a foreground color of your choice.  Make sure the layer is on top of all the other layers.  Choose “Multiply” for the blend mode.

37. 37 In-Classroom Project  Go to Save for web and devices again and save this version lastname_firstname_layerbw02.jpg

38. 38 In-Classroom Project  Now make another new layer on the layer pallete. Name it “Color2” by double clicking the layer name  Fill this layer color with a foreground color that is a darker version of your previous color. My first color was light green, so I’m selecting a dark green.  Make sure layer Color2 is on top of all the other layers.  Choose “Screen” for the blend mode.

39. 39 In-Classroom Project  Go to Save for web and devices again and save this version lastname_firstname_layerbw03.jpg

40. 40 In-Classroom Project  Right-click “color1” and make a duplicate layer called “color1 copy”  Move “color1 copy” to the top of the layer list  Hide both layers “color1” and “color2”  Choose “Difference” for the blend mode.  Make a new adjustment layer, choose Invert

41. 41 In-Classroom Project  Go to Save for web and devices again and save this version lastname_firstname_layerbw04.jpg Difference

42. 42 In-Classroom Project  You should now have 4 JPG images.  Save these 4 JPG’s and your PSD file in your named folder to my computer

43. 43 Homework  Read Chapter 9 and 10 in Digital Foundations before next week.