☰ Contents · Computing

Cropping, transformations and a control work

Lessons 8–9 · 2 lessons · N. I. Taylaqov (general editor), A. B. Akhmedov, M. D. Pardayeva, A. A. Abdug‘aniyev, U. M. Mirsanov. Informatics and Information Technologies, Grade 11, 1st edition. “Extremum-press”, Tashkent, 2018
9

Control work

Textbook: p. 36
GoalChecks what has been learnt about graphics basics, the PhotoShop interface, files, selection and cropping in control tasks.
New words
aspect ratio: width to height, for example 16:9 or 4:3 · tomonlar nisbatiselection modes: new, add, subtract and intersect · ajratma rejimlariraster / vector: a picture of pixels / a picture described by shapes · rastr / vektorPSD keeps layers, JPEG is a lossy photo format, PNG is lossless with transparency · PSD / JPEG / PNG
Explanation

The control work covers lessons 1–8. The theory part asks about the classes of graphics, the pixel and video card, 2D and 3D graphics, the differences between raster, vector and fractal graphics, and PhotoShop's history and interface. The practical part includes opening and saving files, choosing a format for the task, the selection tools, cropping and transformations. The calculation tasks use the number of pixels (width·height), uncompressed size (pixels·3 bytes) and print size (pixels:dpi). To prepare, write out the new terms from each lesson, memorise the tool keys (M, L, W, C, H) and try to explain each answer in your own words. In the practical work save the file first as PSD and check the result before handing it in.

Worked examples
A sample calculation: a phone photo is 4000×3000 pixels. The number of pixels is 4000·3000 = 12 000 000; the uncompressed 24-bit size is 12 000 000·3 = 36 000 000 bytes; printed at 300 dpi its width is 4000:300 ≈ 13.3 inches (about 34 cm).
A sample practical task: open “flower.jpg”, separate the flower from the background with the magnetic lasso or magic wand, do Ctrl+C, Ctrl+V, reduce it to 50%, crop it 1:1 and save it as “flower_work.psd” and “flower_work.png”. For each step you should be able to say which menu or key is used.
Class activity

“Mini control work”: the class splits into two groups; each group writes 5 questions (theory, calculation, practical) for the other and writes the answer key; then the groups swap and solve.

Practice
1
Give one typical example of each of raster, vector and fractal graphics.
2
How many pixels does a 1600×900 display have?
3
Choose the format for each: a) layered work; b) an icon with a transparent background; c) a photo to send by mail.
4
Write the four selection modes and their keys.