Introduction to Photoimpact

S2 Computer Literacy -- Introduction to PhotoImpact (Exercise 1)

Section A Fundamental Concept

A.1 Size of picture

The size of a picture can be measured by the number of horizontal and vertical pixels. A pixel is a point which has a distinguished colour. The larger size of the picture, the larger size of the file storing it and the more time of copying or downloading the file.

A.2 Type of picture

There are several common types of picture files. They include

(a) .BMP (It is called bitmap file which contains pixels of different colours. It will be distorted and blurred if the picture is enlarged.)

(b) .JPG (It saves the picture in compressed format. Because of its small size, it is commonly used in saving pictures used in webpages.)

A.3 Colour Mode of pictures

The following are common colour modes of pictures, arranging in ascending order of file sizes.

1. Black and white. Each pixel of the picture is either black or white.

2. Grayscale. Each pixel represents a certain intensity of gray colour.

3. 256 colour. Each pixel can be one of the 256 predefined colours. The following picture shows some of pre-defined colours.

4. True colour. Using Red, Green and Blue as primary colours, each having 256 levels of intensity, more than 16,000,000 colours can be defined for each pixel. This number of colours is very similar to that of all colours in this real world.

Section B Image Adjustment

B.1 Automation

Select [Format] ® [Auto-process]. There are five elements in which PhotoImpact can help you adjust the image. They are “Brightness & Contrast” (“亮度與對比”), “Hue & Saturation” (“色相與彩度”), “Focus” (“焦距”), “Straighten” (“調正”) and “Crop” (“剪裁”).

After applying auto-adjustment of image by PhotoImpact to the above picture, it becomes

B.2 Style Gallery

You can also choose the pre-saved styles of the software to an image. Select [format] ® [Style]. You can then choose the style you like most according to the type of images, say “building”, from the category bar.

After you have chosen a style, you can preview it before you really apply it to your image.

B.3 Manual Adjustment

You can adjust the five elements manually by directly choosing the functions from the [format] menu.

Section C Area Selection

C.1 Standard Selection Tool

Click the “Standard Selection Tool” from the tool bar and select the shape of portion selected.

C.2 Lasso Tool

Lasso Tool is used to an object with selected irregular shape. You press the left hand sided button of your mouse and “draw” the boundary of the object carefully. Remember to check the “Snap to Edge” option so that the software can help identify the outline of the picture.

The dotted line shows the area selected by the “Lasso Tool” function.

C.3 Magic Wand Tool

“Magic Wand Tool” help you select the part of the picture by identifying the pixels having similar colour with the pixel you have chosen.

Firstly, you should select the “Magic Wand Tool” function from the tool bar. Afterwards, check the box of “+” which means cumulating the areas selected. Use you mouse to click the areas you want consecutively until all the parts you want has been selected.

Section D Area Capturing

D.1 After you have selected the area you want, you can set effects to it by choosing [format] ® [Style]

and apply a style to your selected area and click “OK”. Only the area selected shows the effect.

D.2 Capture the image and save as another file

After you have selected a portion of the picture, you can drag and drop it outside the current window and the part a new picture.

exercise

1. Create a new file and save with GIF format named “exercise.jpg” with the following:

True colour

Background (Canvas) colour: Red

Width, Height: 250 pixels, 300 pxiels

Resolution: 72

2. Open the file “dog.jpg”. Select the dog ONLY inside the picture and save it as a separate file called “dogalone.jpg”, similar to the figure below. (The background colour of the saved picture should be white in colour.)

3. Open the file “yellow flower.jpg”. Select the flower ONLY inside the picture and save it as a separate file called “flower.jpg”, like the figure above. (The background colour of the saved picture should be white in colour.)

Submit your work to your Computer Literacy teacher.

P.1