The automatic camera takes 1600x900 raster images. Control training tasks

All categories of the task Finding volume graphic file Finding volume sound file Transmission speed

1) To store an arbitrary raster image of 128×320 pixels, 40 KB of memory is allocated, excluding the size of the file header. The same number of bits are used to encode the color of each pixel, and the pixel codes are written to the file one after the other without gaps. What is the maximum number of colors that can be used in an image?

2) Automatic camera produces raster images size 200x256 pixels. The same number of bits are used to encode the color of each pixel, and the pixel codes are written to the file one after the other without gaps. The size of the image file cannot exceed 65 KB without taking into account the size of the file header. What is the maximum number of colors that can be used in a palette?

3) A 40 MB document can be transferred from one computer to another in two ways.

A. Compress with an archiver, transfer the archive via a communication channel, unpack.

B. Transmit over a communication channel without using an archiver.

Which method is faster and by how much, if:  the average data transfer speed over the communication channel is 223 bits per second;  the volume of the document compressed by the archiver is 90% of the original;  time required to compress a document – 16 seconds, to decompress – 2 seconds?

In your answer, write the letter A if method A is faster, or B if method B is faster. Immediately after the letter, write a number indicating how many seconds one method is faster than the other. So, for example, if method B faster way And for 23 seconds, you need to write B23 in your answer.

The units of measurement “seconds”, “sec.”, “s” do not need to be added to the answer.

4) Two-channel (stereo) sound recording was made with a sampling frequency of 64 kHz and 24-bit resolution. The result was a file of 120 MB in size; no data compression was performed. Determine approximately how long (in minutes) the recording took place. As an answer, indicate the integer closest to the time of recording, a multiple of 5.

5) What is the minimum amount of memory (in KB) that must be reserved to be able to store any 64x64 pixel bitmap image, assuming that the image can contain 256 different colors? In your answer, write down only an integer; there is no need to write a unit of measurement.

6) To store an arbitrary raster image of 1024×1024 pixels in size, 512 KB of memory are allocated, and for each pixel it is stored binary number– color code of this pixel. For each pixel, the same number of bits are allocated to store the code. Data compression is not performed. What is the maximum number of colors that can be used in an image?

7) The piece of music was digitized and recorded as a file without using data compression. The resulting file was transmitted to city A via a communication channel in 15 seconds. Then the same piece of music was re-digitized with a resolution 2 times higher and a sampling rate 1.5 times lower than the first time. No data compression was performed. The resulting file was transferred to city B; throughput The communication channel with city B is 2 times higher than the communication channel with city A. How many seconds did the file transfer to city B last? In your answer, write down only an integer; there is no need to write a unit of measurement.

8) An automatic camera produces raster images of 640x480 pixels. In this case, the size of the image file cannot exceed 320 KB, and no data packaging is performed. What is the maximum number of colors that can be used in a palette?

9) The musical fragment was recorded in mono format, digitized and saved as a file without using data compression. The size of the resulting file is 24 MB. Then the same piece of music was recorded again in stereo format (two-channel recording) and digitized with a resolution 4 times higher and a sampling rate 1.5 times lower than the first time. No data compression was performed. Specify the file size in MB of the resulting rewrite.

10) The piece of music was digitized and recorded as a file without using data compression. The resulting file was transmitted to city A via a communication channel in 96 seconds. The same piece of music was then re-digitized at a resolution 4 times higher and a sampling rate 3 times lower than the first time. No data compression was performed. The resulting file was transferred to city B in 16 seconds. How many times is the channel capacity to city B greater than the channel capacity to city A?

11) The piece of music was digitized and recorded as a file without using data compression. The resulting file was transmitted to city A via a communication channel in 45 seconds. The same piece of music was then re-digitized at a resolution 4 times lower and a sampling rate 12 times higher than the first time. No data compression was performed. The resulting file was transferred to city B in 15 seconds. How many times is the channel capacity to city B greater than the channel capacity to city A?

Analysis of task 9 of the Unified State Exam 2018 in computer science and ICT from the demo version. This is a task of a basic level of difficulty. Approximate time to complete the task is 5 minutes.

Checked content elements:
— The ability to determine the speed of information transmission for a given channel bandwidth, the amount of memory required to store audio and graphic information.

Task 9

The automatic camera produces raster images of 640x480 pixels. In this case, the size of the image file cannot exceed 320 KB, and no data packaging is performed. What is the maximum number of colors that can be used in a palette?

Answer: ________

Analysis of task 9 of the Unified State Exam 2018 in computer science

The volume of a raster image is calculated as the product of the number of pixels in the image and the amount of memory i , necessary to store the color of one pixel

In our case

640 480 i ≤ 320 1024 8 bits

i ≤ 320 1024 8/(640 480),

since a bit can only be an integer, we get

i=8(in our problem it is said that the size of the image file cannot exceed 320 KB, therefore, we cannot round up! The resulting value i round down to 8 bits!)

To do this we use the formula N = 2i

N = 2 8 = 256

This means that you can use no more than 256 colors.

| Computer Science and Information and Communication Technologies | Preparation for the Unified State Exam | Control training tasks

Control training tasks

Part 1 Task 9

The answers to tasks 1 – 23 are a number, a sequence of letters or numbers that should be written in ANSWER FORM No. 1 to the right of the number of the corresponding task, starting from the first cell, without spaces, commas and other additional characters. Write each character in a separate box in accordance with the samples given in the form.

Example 1

What is the minimum amount of memory (in KB) that must be reserved to be able to store any 64x64 pixel bitmap image, assuming that the image can contain 256 different colors? In your answer, write down only an integer; there is no need to write a unit of measurement.

Example 2

To store an arbitrary raster image of 1024x1024 pixels in size, 512 KB of memory is allocated, and for each pixel a binary number is stored - the color code of this pixel. For each pixel, the same number of bits are allocated to store the code. Data compression is not performed. What is the maximum number of colors that can be used in an image?

Answer: ___________________________.

Example 3

For completing the task correctly you will receive 1 point. It takes approximately 5 minutes.

To complete task 9 in computer science you need to know:

I - volume of information
to store a bitmap you need to allocate memory I = N i bits, where N– number of pixels and i– color depth (encoding bit depth)
number of image pixels N calculated as the product of the image width and height (in pixels)
coding depth is the number of bits allocated to store the color of one pixel
The volume of a music file is calculated using formula I = f*r*k*t, Where f- sampling frequency, r– resolution (encoding depth), k– number of channels, t – playing time
channel B capacity = f*r*k

Tasks for training

Task No. 1

Task No. 2

To store an arbitrary raster image of 256×1024 pixels in size, 64 KB of memory is allocated, and for each pixel a binary number is stored - the color code of this pixel. For each pixel, the same number of bits are allocated to store the code. Data compression is not performed. What is the maximum number of colors that can be used in an image?

Task No. 3

What is the minimum amount of memory (in KB) that must be reserved to be able to store any 512-by-128-pixel bitmap image, assuming that the image can use 512 different colors? In your answer, write down only an integer; there is no need to write a unit of measurement.

Task No. 4

The musical fragment was recorded in stereo format (two-channel recording), digitized and saved as a file without using data compression. The size of the resulting file is 100 MB. The same piece of music was then re-recorded in mono and digitized at a resolution 3 times higher and a sampling rate 5 times lower than the first time. No data compression was performed. Specify the file size in MB of the resulting rewrite. In your answer, write down only an integer; there is no need to write a unit of measurement.

. Information coding, volume and transmission of information: demo version Unified State Examination Computer Science 2019; state final exam 2019; training versions of the Unified State Exam in computer science, thematic test tasks and tasks from the computer science simulator 2019

✍ Solution:

Let's remember the basic formula for the volume of an image file:

I = m * n * i

m, n — resolution (width and height in pixels)
i — color coding depth

We express all values in powers of two:

200|2 100|2 50 |2 25 | 25 * 2 3

Permission:

25 * 2 3 * 2 8 = 25 * 2 11

Let's substitute all the values:

i * 25 * 2 11

Because the i must be less than the obtained value, then i=10.

Let's count the number of colors:

colors = 2 i = 2 10 = 1024

Result: 1024

9 Unified State Exam 2019 tasks for training

Option No. 3, 2019 (10 options), S.S. Krylov, T.E. Churkina:

800×2800 700 KB

Which

Answer: 4

Option No. 4, Model exam options 2019 (10 options), S.S. Krylov, T.E. Churkina:

An automatic camera produces raster images of size 1000×1600 pixels. The same number of bits are used to encode the color of each pixel, and the pixel codes are written to the file one after the other without gaps. The size of the image file cannot exceed 2100 KB excluding the size of the file header.

Which maximum number of colors can it be used in a palette?

Answer: 1024

Option No. 8, Model exam options 2019 (10 options), S.S. Krylov, T.E. Churkina:

Which minimum memory size (in KB) needs to be reserved so that any bitmap size can be saved 1280 x 80 pixels provided that the image may be used 64 different colors? In your answer, write down only an integer; there is no need to write a unit of measurement.