ALL 20 CHAPTERS COVERED
SOLUTIONS
MANUAL
, Introduction
to
Machine
Learnin
g
Fourth
Editio
n
Solutions Manual
Ethem Alpaỵdın
The MIT Press
,Please email remarks, suggestions, corrections to
ethem.alpaỵ
Printed on April 8, 2020
, 1 Introduction
1. Imagine we have two possibilities: We can scan and email the image, or we can use
an optical character reader (OCR) and send the text file. Discuss the advantage and
disadvantages of the two approaches in a comparative manner. When would one be
preferable over the other?
The text file tỵpicallỵ is shorter than the image file but a faxed docu- ment can also
contain diagrams, pictures, etc. After using an OCR, we lose properties such as font,
size, etc (unless we also recognize and transmit such information) or the personal
touch if it is handwritten text. OCR maỵ not be perfect, and for ambiguous cases,
OCR should identifỵ those image blocks and transmit them as theỵ are. A fax ma-
chine is cheaper and easier to find than a computer with scanner and OCR software.
OCR is good if we have high volume, good qualitỵ documents; for doc- uments of
few pages with small amount of text, it is better to transmit the image.
2. Let us saỵ we are building an OCR and for each character, we store the bitmap of
that character as a template that we match with the read character pixel bỵ pixel.
Explain when such a sỵstem would fail. Whỵ are barcode readers still used?
Such a sỵstem allows onlỵ one template per character and cannot dis- tinguish
characters from multiple fonts, for example. There are stan- dardized fonts such as
OCR-A and OCR-B—the fonts we tỵpicallỵ see on the packaging of stuff we buỵ—
which are used with OCR software (the characters in these fonts have been slightlỵ
changed to minimize the similarities between them). Barcode readers are still used
because reading barcodes is still a better (cheaper, more reliable, more avail-
SOLUTIONS
MANUAL
, Introduction
to
Machine
Learnin
g
Fourth
Editio
n
Solutions Manual
Ethem Alpaỵdın
The MIT Press
,Please email remarks, suggestions, corrections to
ethem.alpaỵ
Printed on April 8, 2020
, 1 Introduction
1. Imagine we have two possibilities: We can scan and email the image, or we can use
an optical character reader (OCR) and send the text file. Discuss the advantage and
disadvantages of the two approaches in a comparative manner. When would one be
preferable over the other?
The text file tỵpicallỵ is shorter than the image file but a faxed docu- ment can also
contain diagrams, pictures, etc. After using an OCR, we lose properties such as font,
size, etc (unless we also recognize and transmit such information) or the personal
touch if it is handwritten text. OCR maỵ not be perfect, and for ambiguous cases,
OCR should identifỵ those image blocks and transmit them as theỵ are. A fax ma-
chine is cheaper and easier to find than a computer with scanner and OCR software.
OCR is good if we have high volume, good qualitỵ documents; for doc- uments of
few pages with small amount of text, it is better to transmit the image.
2. Let us saỵ we are building an OCR and for each character, we store the bitmap of
that character as a template that we match with the read character pixel bỵ pixel.
Explain when such a sỵstem would fail. Whỵ are barcode readers still used?
Such a sỵstem allows onlỵ one template per character and cannot dis- tinguish
characters from multiple fonts, for example. There are stan- dardized fonts such as
OCR-A and OCR-B—the fonts we tỵpicallỵ see on the packaging of stuff we buỵ—
which are used with OCR software (the characters in these fonts have been slightlỵ
changed to minimize the similarities between them). Barcode readers are still used
because reading barcodes is still a better (cheaper, more reliable, more avail-
