Multimedia (Cambridge (CIE) A Level Computer Science): Exam Questions

A computer system stores text, images and sound.

The colour of each pixel in a bitmapped image is represented by 8 bits.

(i) State the largest number of different colours that can be represented by 8 bits.

(1)

(ii) State one drawback of increasing the number of bits that represents each pixel in the bitmap image.

(1)

(i) Explain how an analogue sound wave is converted into digital data.

(2)

(ii) Describe one method of compressing a sound file using lossy compression.

(2)

The digital camera has a microphone which is used to record the sound for the video.

The user changes the sampling rate that the microphone uses from 44.1kHz to 88.2kHz.

Describe how this change in sampling rate will affect the performance of the video doorbell.

The computer can transmit a video made from bitmap images and vector graphic animations to the VR headset.

(i) Describe how the data for a bitmapped image is encoded.

(3)

(ii) Describe the contents of a vector graphic drawing list.

(2)

A photograph is stored as a bitmap image.

The photograph has a resolution of 4000 pixels wide by 3000 pixels high. The bit depth is 4 bytes.

Calculate an estimate for the file size of the photograph in megabytes.

Show your working.

Identify two elements of a bitmap image that can be changed to reduce its file size.

Draw one line from each vector graphic term to its most appropriate description.

State what is meant by the bit depth of a bitmap image and explain how changing the bit depth affects the image.

Explain the impact of changing the sampling resolution on the accuracy of a sound recording.

A bitmap image has a resolution of 2048 pixels wide and 1024 pixels high.

The image has a bit depth of 10 bits per pixel.

Estimate the file size of the bitmap image in mebibytes. Show your working.

State what is meant by analogue data.

Draw one line from each term to its most appropriate description.

Describe the impact of increasing the image resolution on the quality of a bitmap graphic.

Calculate the file size of a bitmap image using the following information:

• image resolution of 2048 pixels wide and 1024 pixels high

• bit depth of 16 bits.

Give your answer in kibibytes. Show your working.

A design company stores a company logo as a vector graphic.

The logo contains a circle.

(i) State what is meant by the term drawing object.

(1)

(ii) State one property that is stored for the circle.

(1)

A vector graphic of a road sign is stored on a computer.

The graphic is enlarged to four times its original width and height.

Explain why the quality of the enlarged graphic does not decrease.

An airport stores a floor plan of a terminal building as a vector graphic.

The plan contains 400 drawing objects.

The airport makes two changes to the plan:

• every wall is drawn with a thicker line

• one extra doorway is added

Describe how the vector graphic file is changed to make these two changes.

Use the terms drawing list, drawing object and property in your answer.

A design company must choose a file format for each of four images.

Complete the table by writing either bitmap image or vector graphic in each empty cell, to show the more suitable format for each image.

A museum is designing a new sign for the entrance to each of its rooms.

Each sign shows the name of the room and a simple arrow.

The same design will be printed at three sizes: on a small card, on a wall panel and on a large banner outside the building.

Justify the use of a vector graphic rather than a bitmap image for the sign design.

A wildlife charity is creating a new website.

The website will use two types of image:

• photographs of animals taken with a camera

• the charity logo, which appears as a small icon in the corner of every page and as a large image on the home page

Compare the use of bitmap images and vector graphics for storing these two types of image.

A digital camera stores each photograph it takes as a bitmap image.

State what is meant by each of the following terms.

(i) Pixel

(1)

(ii) Image resolution

(1)

A student records their voice using a microphone. The recording is stored as a digital sound file.

State what is meant by sampling rate and what is meant by sampling resolution.

A company logo is stored as a bitmap image. The logo uses exactly 40 different colours.

(i) Calculate the minimum colour depth, in bits per pixel, that can be used to store the logo.

Show your working.

(2)

(ii) State how many further different colours could be added to the logo at this colour depth, without increasing the colour depth.

(1)

A musician records a song using a microphone connected to a computer. The song is stored on the hard disk of the computer as a digital sound file.

Describe how the analogue sound wave is converted into the digital data that is stored.

A microscope is connected to a computer. Each image captured by the microscope is saved as an uncompressed bitmap file.

Explain how the data for the image is encoded in the file, and why the file header is needed when the file is opened again.

A device records sound using a sampling resolution of 3 bits.

The amplitude of the sound wave is measured on a scale from 0 to 8 units.

The device divides this scale into 8 equal levels, numbered 0 to 7:

• level 0 stores any amplitude from 0 up to but not including 1

• level 1 stores any amplitude from 1 up to but not including 2

• this pattern continues up to level 7, which stores any amplitude from 7 up to 8

The level number is then stored as a 3-bit binary value.

Complete the table for the four samples shown.

A bitmap image has an image resolution of 320 pixels wide by 256 pixels high.

The colour depth is 4 bits per pixel.

Calculate an estimate for the file size of the image. Give your answer in kibibytes.

Ignore the size of the file header.

Show your working.

A voice message is recorded and saved as a digital sound file.

Tick (✓) one box in each row to identify the effect of each change on the size of the sound file.

A camera saves each photograph as an uncompressed bitmap file.

Each photograph has an image resolution of 1024 pixels wide by 768 pixels high, and a colour depth of 24 bits per pixel.

Calculate an estimate for the file size of one photograph. Give your answer in mebibytes.

Ignore the size of the file header.

Show your working.

A sound file is recorded using:

• a sampling rate of 40 kHz

• a sampling resolution of 16 bits

• a length of 5 minutes

Calculate the size of the sound file. Give your answer in megabytes and show your working.

Use 1 kilobyte = 1000 bytes and 1 megabyte = 1000 kilobytes.

A wildlife camera saves each photograph as an uncompressed bitmap file.

Each file contains:

• pixel data for an image with an image resolution of 1024 pixels wide by 1024 pixels high

• a colour depth of 8 bits per pixel

• a file header of 1024 bytes

(i) Calculate the total size of one file, including the file header. Give your answer in kibibytes.

Show your working.

(2)

(ii) The camera has 20 mebibytes of storage available for photographs.

Calculate the largest number of complete files the camera can store.

Show your working.

(2)

A student records a voice message that is 2 minutes long. The recording uses a sampling rate of 44.1 kHz and a sampling resolution of 16 bits.

The student wants to copy the file to a memory stick that has 6 megabytes of free space.

Calculate the size of the sound file in megabytes and state whether the file will fit in the free space.

Then give one change to the sampling settings that would make the file fit, showing the new file size, and describe the effect that your change would have on the accuracy of the recording.

Use 1 megabyte = 1 000 000 bytes.

A bitmap image is saved with a colour depth of 4 bits per pixel.

The colour depth is then changed to 8 bits per pixel. The image resolution does not change.

State the effect of this change on each of the following.

(i) The number of different colours that can be used in the image

(1)

(ii) The file size of the image

(1)

A photograph is scanned to produce a bitmap image.

The same photograph is then scanned a second time. For the second scan, the width in pixels and the height in pixels are both doubled. The colour depth is not changed.

(i) Describe the effect of this change on the quality of the second image.

(1)

(ii) Describe the effect of this change on the file size of the second image. Include how many times larger the file size becomes.

(2)

A travel website shows one photograph of each hotel.

Each photograph is stored on the web server as an uncompressed bitmap image with an image resolution of 3000 pixels wide by 2000 pixels high.

Every photograph is displayed on the web page inside an area that is 600 pixels wide by 400 pixels high.

The website owner decides to store each photograph at an image resolution of 600 pixels wide by 400 pixels high instead.

Explain why this decision is suitable for the website, and give one situation in which the original photographs would still be needed.