Scientific Imaging Wednesday, February 01, 2017 Basics of Photoshop

Transcription

1 Scientific Imaging Wednesday, February 01, 2017 Basics of Photoshop When you are done with this class, you should be able to: 1. Distinguish between image management and image editing software and know when to use each. 2. Know how to review images in Adobe Bridge and/or FastStone and select promising images to open in Photoshop 3. Open an image in Photoshop. 4. Set up the Photoshop window and examine an image s metadata and histogram. 5. Crop an image to enhance composition. 6. Size an image to fit its intended use. 7. Understand layers as they apply to Photoshop. 8. Adjust brightness and contrast. 9. Adjust color balance. 10. Make selections 11. Add text, arrows, border, etc. 12. Save an image in an appropriate format. 13. Sharpen an image 1. Distinguish between image management and image editing software and know when to use each. Two basic types of image software: Image management software is used to review, sort, and sometimes present images. Usually has limited ability to modify images Usually supplied with digital cameras. 3 rd party solutions often more capable FastStone: i. Install ii. Freeware! iii. Show light table, slideshow, histogram, screen capture Bridge i. Open ii. Comes with Photoshop 1. Lightroom 2. Aperture iii. Show basic setup, metadata, filters

2 2. Know how to review images in Adobe Bridge and/or FastStone and select promising images to open in Photoshop Go to scratch drive and open exposures assignment folder Review files, find own 3. Open an image in Photoshop. Select flower_3442.jpg and open in Photoshop 4. Set up the Photoshop window and examine an image s metadata and histogram. Show windows: i. File info ii. Histogram iii. Info iv. Navigator v. Layers vi. History vii. Turn on grids 5. Crop an image to enhance composition. Demonstrate crop with rectangular marquee Add border: i. Demonstrate concept of canvas ii. Demonstrate eyedropper iii. Demonstrate magic wand iv. Demonstrate paint bucket. 6. Size an image to fit its intended use. Pixels per inch: i for on screen use ii for printing Reset resolution first without resampling Image size: i. For onscreen use, depends on monitor size in pixels ii. For printing, depends on media size in inches iii. Initially, reduce to largest projected use (usually print) Adjust image to max of 1800 x 1200 pixels at 72 ppi Use fit on screen

3 7. Understand layers as they apply to Photoshop. Layers 3 types: i. Image information (raster) ii. Graphics (vector) iii. Adjustment Demo use infrared images. Viewing i. Topmost layer overshadows those below it ii. Transparency lets lower levels be seen. iii. Demonstrate eye and active layer: 1. Use layer:duplicate layer and image:adjustments:replace color to create yellow flower on separate layer. 8. Adjust brightness and contrast. Method 1 brightness/contrast control little control! Linear Method 2 autolevels explain theory using histogram Method 3 levels Method 4 levels adjustment layer i. Use adjustment layer to adjust levels Method 5 Curves, including auto Method 6 shadow/highlights 9. Adjust color balance. Use adjustment layer/color balance Estimate need to adjust based on brightest pixel AutoColor 10. Make selections Demonstrate selection techniques: i. Marquees 1. add to/subtract, etc. 2. styles ii. Lassos change cursor style before magnetic iii. Magic wand discuss tolerance, contiguous, inverse selection

4 11. Add text, arrows, border, etc. These should be added as separate layers (text layers automatically separate) Add arrow pointing to anther i. Add new layer and make sure it is selected ii. Choose color 1. demo foreground/background color, swap, color picker 2. demo layer style, stroke Add text for anther and name i. Demo styles, save style 12. Save an image in an appropriate format. This is a good point to save the file: i. Save as photoshop file to maintain layers 1. large, but 2. can be submitted in this format 3. can be reopened and edited easily 4. no loss of image quality 5. need photoshop to open ii. TIFF 1. also supports layers 2. smaller than PSD 3. Can be read by many programs 4. some features not supported iii. BMP 1. no layers, no compression 2. smaller than layered files 3. used directly by windows iv. JPG 1. smallest 2. compressed 3. some quality loss 4. no layers 5. widely used on web 6. beware artifacts v. RAW 1. Large 2. Much more information 14 bit 3. No quality loss 4. Can be edited non-destructively via sidecar (XMP) files 5. No layers 6. Restricted as to software

5 vi. Other formats: 1. GIF 2. PNG 3. Etc. Save as Photoshop at this point Sharpen an image Normally next-to-last step Never resize or apply filters after sharpening Be sure image layers are active (as opposed to text, adjustment, etc.) May want to make copy of layer first, apply filter to copy and hide original Demonstrate unsharp mask i. Use shake reduction in Photoshop CC Always judge sharpness at actual pixels!!! Save as jpg copy Now: Work on your labeled apparatus picture!