問12
頻出度★★☆
QR コードの特徴として, 適切なものはどれか。
平成26年度 春期 ITパスポート試験 問12
ストラテジ系法務 › 標準化関連
This question's explanation and your answers so far.
解説
問 12
Incorrectア
Incorrect. Far from excluding kanji, a QR code has a kanji mode for storing kanji and kana efficiently. It encodes data by switching among modes such as numeric, alphanumeric, 8-bit byte (symbols and various characters), and kanji, so it can store strings including Japanese as they are — which is in fact an advantage of the QR code.
Incorrectイ
Incorrect. A one-dimensional barcode (for example, a JAN code) can represent only about 13 digits, whereas a QR code arranges cells in two dimensions, so it can hold orders of magnitude more information in the same area. The amount of information is not “the same”; large capacity is the main reason for using a two-dimensional code.
- ウ
正解 The correct answer is ウ “The code can be read from any direction: up, down, left, or right.” A QR code is a matrix-type two-dimensional code in which light and dark cells (squares) are arranged in a grid of rows and columns. One of its most important features is the large double-square marks placed at three corners of the symbol — the position detection patterns (finder patterns). A reader first locates these three marks and, from their positional relationship, instantly calculates the center, size, tilt, and orientation of the code. As a result, the code can be decoded in the same way whether it is sideways, upside down, or slanted, and the user can simply hold it up without worrying about which way it faces. A one-dimensional barcode can in principle be read only from a fixed direction (the direction in which the scanning line crosses the bars), whereas a QR code can be read quickly from any of 360 degrees thanks to this structure — which is why it has spread to a wide range of uses such as in-store payment, product tags, and passing along URLs.
Incorrectエ
Incorrect. Two-dimensional codes come in a stacked type, in which narrow barcodes are piled up in several rows (such as PDF417), and a matrix type, in which light and dark cells are arranged in a grid; a QR code is the latter, a matrix type. The description “a structure formed by stacking three layers of barcodes” mistakes the characteristics of the stacked type, and moreover the number of rows is not fixed at three.
ここがポイント
- A QR code is a matrix-type two-dimensional code. The position detection patterns (finder patterns) at three corners let the reader determine orientation and tilt, so the code can be read from any direction: up, down, left, or right. It also has an error-correction function, so it can be restored even if part of the code is dirty or missing — another important feature.
- Learn it by comparison with the one-dimensional barcode: a barcode carries information only in the horizontal direction, so its capacity is small and its reading direction is limited, whereas a two-dimensional code carries information both vertically and horizontally, has a large capacity, and can also store characters including kanji. Two-dimensional codes come in stacked types (such as PDF417) and matrix types (such as the QR code).
用語