Epson GT-300, GT-1000, GT-6000, ES-300GS, GT-8500 User Manual

...

EPSON® ESC/ITM Scanner

GT-1000 GT-4000 GT-6000 ES-300C GT-6500 ES-600C GT-8000 ES-800C GT-8500 ES-1000C GT-9000 ES-1200C GT-5000 Action Scanner II GT-300 ES-300GS

Reference Manual

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of Seiko Epson Corporation. No patent liability is assumed with respect to the use of the information contained herein. While every precaution has been taken in the preparation of this book, Seiko Epson Corporation assumes no responsibility for errors or omissions. Neither is any liability assumed for damages resulting from the use of the information contained herein.

Seiko Epson Corporation shall not be liable against any damages or problems arising from the use of any options other than those designated as Original Epson Products by Seiko Epson Corporation.

EPSON is a registered trademark of Seiko Epson Corporation. EPSON ESC/I is a trademark of Seiko Epson Corporation. HP PaintJet is a trademark of Hewlett-Packard Company. Apple and Macintosh are trademarks of Apple Computer, Inc.

Preface

This manual was designed to be a comprehensive guide to programming EPSON scanners using the advanced ESC/I control language. It was written with both the professional and advanced hobbyist programmer in mind.

Before you begin using this manual, you should thoroughly review the operating instructions in your scanner’s user’s guide.

iii

Contents

Introduction

Manual Construction . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Command Usage . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Command Reference . . . . . . . . . . . . . . . . . . . . . . . 1-2

Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Using This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

To understand EPSON scanners . . . . . . . . . . . . . . . . . 1-3

To write a scanner control program . . . . . . . . . . . . . . . 1-3

Chapter 1 Overview

What Is a Scanner . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Basic scanning principles . . . . . . . . . . . . . . . . . . . . 1-2

Reading color . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

Reading monochrome . . . . . . . . . . . . . . . . . . . . . . 1-4

EPSON Scanner Features . . . . . . . . . . . . . . . . . . . . . . . 1-5

Control Code Construction . . . . . . . . . . . . . . . . . . . . . . 1-7

Function level . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

Computers and Handshaking . . . . . . . . . . . . . . . . . . . . . 1-8

Image Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9

Image data format . . . . . . . . . . . . . . . . . . . . . . . . 1-9

Line data transfer . . . . . . . . . . . . . . . . . . . . . . . . 1-11

Block data transfer . . . . . . . . . . . . . . . . . . . . . . . . 1-12

Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13

Image definition . . . . . . . . . . . . . . . . . . . . . . . . . 1-13

Gamma correction . . . . . . . . . . . . . . . . . . . . . . . . 1-14

Data form definition . . . . . . . . . . . . . . . . . . . . . . . 1-16

Image processing . . . . . . . . . . . . . . . . . . . . . . . . 1-21

Using Scanner Features . . . . . . . . . . . . . . . . . . . . . . . . . 1-23

Scanning multiple shade documents for

output on devices capable of expressing

multiple shades. . . . . . . . . . . . . . . . . . . . . . . . . . 1-23

Scanning multiple shade documents for

bi-level output devices capable of black

and white only . . . . . . . . . . . . . . . . . . . . . . . . . . 1-24

Scanning documents without multiple

shades . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-24

Scanning documents to obtain unprocessed

data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-24

Chapter 2 Command Usage

Execution Commands . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

1. Start scanning (ESC G) . . . . . . . . . . . . . . . . . . . . . 2-2

2. Request ID (ESC I) . . . . . . . . . . . . . . . . . . . . . . . 2-3

3. Request Status (ESC F) . . . . . . . . . . . . . . . . . . . . 2-3

4. Extended Status Request (ESC f) . . . . . . . . . . . . . . . 2-3

5. Request condition (ESC S) . . . . . . . . . . . . . . . . . . . 2-4

Data Form Commands . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

1. Set Color Mode (ESC C) . . . . . . . . . . . . . . . . . . . . 2-5

2. Set Data Format (ESC D) . . . . . . . . . . . . . . . . . . . 2-5

3. Set Resolution (ESC R) . . . . . . . . . . . . . . . . . . . . 2-7

4. Set zoom (ESC H) . . . . . . . . . . . . . . . . . . . . . . . 2-7

5. Set scanning area (ESC A) . . . . . . . . . . . . . . . . . . . 2-8

6. Set data order (ESC K) . . . . . . . . . . . . . . . . . . . . . 2-8

Image Setting Commands . . . . . . . . . . . . . . . . . . . . . . . 2-9

1. Set brightness (ESC L) . . . . . . . . . . . . . . . . . . . . . 2-9

2. Set gamma correction (ESC Z) . . . . . . . . . . . . . . . . . 2-10

3. Download gamma table (ESC z) . . . . . . . . . . . . . . . . 2-12

Image Processing Commands . . . . . . . . . . . . . . . . . . . . . 2-13

1. Set halftoning mode (ESC B) . . . . . . . . . . . . . . . . . 2-13

2. Download dither pattern (ESC b) . . . . . . . . . . . . . . . 2-15

3. Set color correction (ESC M) . . . . . . . . . . . . . . . . . 2-16

4. Download color correction (ESC m) . . . . . . . . . . . . . . 2-17

Auxiliary Commands . . . . . . . . . . . . . . . . . . . . . . . . . 2-18

1. Initialize the scanner (ESC @) . . . . . . . . . . . . . . . . 2-18

2. Set the scanning mode (ESC g) . . . . . . . . . . . . . . . . 2-18

3. Set the line counter (ESC d) . . . . . . . . . . . . . . . . . 2-19

4. Control option (ESC e) . . . . . . . . . . . . . . . . . . . . 2-20

5. Eject (FF) . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-20

Control Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-20

1. Header (STX) . . . . . . . . . . . . . . . . . . . . . . . . . 2-20

2. Abort scanning (CAN) . . . . . . . . . . . . . . . . . . . . 2-21

3. Normal response (ACK) . . . . . . . . . . . . . . . . . . . 2-21

4. Negative response (NAK) . . . . . . . . . . . . . . . . . . . 2-21

Command Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-22

ID information . . . . . . . . . . . . . . . . . . . . . . . . . . 2-22

Control flow . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-23

Recommended command order . . . . . . . . . . . . . . . . . 2-24

Using commands when options are

installed . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-24

Data Block Transfer Order . . . . . . . . . . . . . . . . . . . . . . 2-26

Data block structure . . . . . . . . . . . . . . . . . . . . . . . 2-26

Information block . . . . . . . . . . . . . . . . . . . . . . . . 2-27

Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-30

Transfer order . . . . . . . . . . . . . . . . . . . . . . . . . . 2-32

Scanning Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-35

Resolution, zoom, and maximum scannable

area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-36

Setting the scanning area . . . . . . . . . . . . . . . . . . . . 2-38

Image trimming (1) . . . . . . . . . . . . . . . . . . . . . . . 2-40

Image trimming (2) . . . . . . . . . . . . . . . . . . . . . . . 2-42

Error Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-44

Command error . . . . . . . . . . . . . . . . . . . . . . . . . 2-44

Communications error . . . . . . . . . . . . . . . . . . . . . . 2-44

System error . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-45

Option error . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-46

Function Level and Commands . . . . . . . . . . . . . . . . . . . . 2-47

Using the function level . . . . . . . . . . . . . . . . . . . . . 2-47

Commands and function level table . . . . . . . . . . . . . . . 2-48

Items not affected by function level . . . . . . . . . . . . . . . 2-50

Typical Programming Errors and Solutions . . . . . . . . . . . . . 2-51

vii

Chapter 3 Command Reference

Summary of the Scanner Commands . . . . . . . . . . . . . . . . . . 3-2

Format of the Command Reference . . . . . . . . . . . . . . . . . . 3-4

Execution Commands . . . . . . . . . . . . . . . . . . . . . . . . . 3-6

Data Form Definition Commands . . . . . . . . . . . . . . . . . . . 3-18

Image Definition Commands . . . . . . . . . . . . . . . . . . . . . . 3-36

Image Processing Commands . . . . . . . . . . . . . . . . . . . . . 3-45

Auxiliary Commands . . . . . . . . . . . . . . . . . . . . . . . . . . 3-57

Control Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-65

Appendix A Interface Specifications

Serial Interface Specifications . . . . . . . . . . . . . . . . . . . . . A-2

Signal pin assignments . . . . . . . . . . . . . . . . . . . . . . A-3

Cable wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3

Parallel Interface Specifications . . . . . . . . . . . . . . . . . . . . A-4

Signal pin assignments . . . . . . . . . . . . . . . . . . . . . . A-5

Timing charts . . . . . . . . . . . . . . . . . . . . . . . . . . . A-7

SCSI Interface Specifications . . . . . . . . . . . . . . . . . . . . . A-8

Basic Specification . . . . . . . . . . . . . . . . . . . . . . . . A-8

SCSI Operation Procedure . . . . . . . . . . . . . . . . . . . . . . . A-13

Communication Operation . . . . . . . . . . . . . . . . . . . . A-13

SCSI Commands . . . . . . . . . . . . . . . . . . . . . . . . . A-15

Unit Attention Condition . . . . . . . . . . . . . . . . . . . . . A-16

Sense Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-17

Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-19

Default settings . . . . . . . . . . . . . . . . . . . . . . . . . . A-19

viii

Appendix B Scanner Model Technical Data

GT-1000 Technical Data . . . . . . . . . . . . . . . . . . . . . . . B-2

Physical Characteristics . . . . . . . . . . . . . . . . . . . . . B-2

Error Indications . . . . . . . . . . . . . . . . . . . . . . . . . B-2

Software Functions and Settings . . . . . . . . . . . . . . . . B-3

Software Defaults . . . . . . . . . . . . . . . . . . . . . . . . B-3

DIP Switch Setting . . . . . . . . . . . . . . . . . . . . . . . . B-4

The Identity Data-Block . . . . . . . . . . . . . . . . . . . . . B-6

The Condition Data-Block . . . . . . . . . . . . . . . . . . . . B-7

GT-4000 Technical Data . . . . . . . . . . . . . . . . . . . . . . . B-9

Physical Characteristics . . . . . . . . . . . . . . . . . . . . . B-9

Error Indications . . . . . . . . . . . . . . . . . . . . . . . . . B-9

Software Functions and Settings . . . . . . . . . . . . . . . . B-10

Software Defaults . . . . . . . . . . . . . . . . . . . . . . . . B-11

DIP Switch Setting . . . . . . . . . . . . . . . . . . . . . . . . B-12

The Identity Data-Block . . . . . . . . . . . . . . . . . . . . . B-15

The Condition Data-Block . . . . . . . . . . . . . . . . . . . . B-17

GT-6000 (ES-300C) Technical Data . . . . . . . . . . . . . . . . . B-19

Physical Characteristics . . . . . . . . . . . . . . . . . . . . . B-19

Error Indications . . . . . . . . . . . . . . . . . . . . . . . . . B-19

Software Functions and Settings . . . . . . . . . . . . . . . . B-20

Software Defaults . . . . . . . . . . . . . . . . . . . . . . . . B-21

DIP Switch Setting . . . . . . . . . . . . . . . . . . . . . . . . B-22

The Identity Data-Block . . . . . . . . . . . . . . . . . . . . . B-25

The Condition Data-Block . . . . . . . . . . . . . . . . . . . . B-28

GT-6500 (ES-600C) Technical Data . . . . . . . . . . . . . . . . . B-30

Physical Characteristics . . . . . . . . . . . . . . . . . . . . . B-30

Error Indications . . . . . . . . . . . . . . . . . . . . . . . . . B-31

Software Functions and Settings . . . . . . . . . . . . . . . . B-32

Software Defaults . . . . . . . . . . . . . . . . . . . . . . . . B-33

DIP Switch Setting . . . . . . . . . . . . . . . . . . . . . . . . B-34

The Identity Data-Block . . . . . . . . . . . . . . . . . . . . . B-38

The Condition Data-Block . . . . . . . . . . . . . . . . . . . . B-41

GT-8000 (ES-800C) Technical Data . . . . . . . . . . . . . . . . . . B-43

Physical Characteristics . . . . . . . . . . . . . . . . . . . . . . B-43

Error Indications . . . . . . . . . . . . . . . . . . . . . . . . . B-43

Software Functions and Settings . . . . . . . . . . . . . . . . . B-44

Software Defaults . . . . . . . . . . . . . . . . . . . . . . . . . B-45

The Identity Data-Block . . . . . . . . . . . . . . . . . . . . . B-46

The Condition Data-Block . . . . . . . . . . . . . . . . . . . . B-49

GT-8500 (ES-1000C) Technical Data . . . . . . . . . . . . . . . . . B-51

Physical Characteristics . . . . . . . . . . . . . . . . . . . . . . B-51

Error Indications . . . . . . . . . . . . . . . . . . . . . . . . . B-51

Software Functions and Settings . . . . . . . . . . . . . . . . . B-52

Software Defaults . . . . . . . . . . . . . . . . . . . . . . . . . B-53

The Identity Data-Block . . . . . . . . . . . . . . . . . . . . . B-54

The Condition Data-Block . . . . . . . . . . . . . . . . . . . . B-57

GT-9000 (ES-1200C) Technical Data . . . . . . . . . . . . . . . . . B-60

Physical Characteristics . . . . . . . . . . . . . . . . . . . . . . B-60

Error Indications . . . . . . . . . . . . . . . . . . . . . . . . . B-60

Software Functions and Settings . . . . . . . . . . . . . . . . . B-61

Software Defaults . . . . . . . . . . . . . . . . . . . . . . . . . B-62

The Identity Data-Block . . . . . . . . . . . . . . . . . . . . . B-63

The Condition Data-Block . . . . . . . . . . . . . . . . . . . . B-67

GT-5000 (Action Scanner II) Technical Data . . . . . . . . . . . . . B-69

Physical Characteristics . . . . . . . . . . . . . . . . . . . . . . B-69

Error Indications . . . . . . . . . . . . . . . . . . . . . . . . . B-69

Software Functions and Settings . . . . . . . . . . . . . . . . . B-70

Software Defaults . . . . . . . . . . . . . . . . . . . . . . . . . B-71

The Identity Data-Block . . . . . . . . . . . . . . . . . . . . . B-72

The Condition Data-Block . . . . . . . . . . . . . . . . . . . . B-75

GT-300 (ES-300GS) Technical Data . . . . . . . . . . . . . . . . . . B-78

Physical Characteristics . . . . . . . . . . . . . . . . . . . . . . B-78

Error Indications . . . . . . . . . . . . . . . . . . . . . . . . . B-78

Software Functions and Settings . . . . . . . . . . . . . . . . . B-79

Software Defaults . . . . . . . . . . . . . . . . . . . . . . . . . B-80

The Identity Data-Block . . . . . . . . . . . . . . . . . . . . . B-81

The Condition Data-Block . . . . . . . . . . . . . . . . . . . . B-84

Introduction

Introduction 1

Manual Construction

This manual consists of the following sections:

❏ Overview ❏ Command Usage ❏ Command Reference ❏ Appendix

The contents of each of these sections is described below:

Overview

Presents an overview of scanner functions, EPSON scanner features, control codes, and programming concepts. This information is helpful in quickly understanding scanner operating concepts.

Command Usage

Provides recommended ESC/I command usage and program construction for optimum use of EPSON scanner features. This section also provides information on image data transfer, the scanning environment, and error handling.

Command Reference

Lists each ESC/I command and its parameters in detail.

Appendix

Offers additional information necessary for writing scanner programs. This includes the specifications for each type of interface, command support levels, and available scanner options.

2 Introduction

Using This Manual

To get the most out of this manual, you should follow the steps below:

To understand EPSON scanners

Read through the overview once, and then read the Command Usage section in depth.

To write a scanner control program

Read through the overview once, then read the Command Usage section. From there, move to the Command Reference section, followed by the Appendix.

Always refer to the Appendix to ensure that the interface and data types correspond to your target scanner models.

Also, several examples of common programming errors and information on resolving these errors are included.

Introduction 3

4 Introduction

Chapter 1

Overview

This chapter provides a brief description of scanner operations and concepts. The special features of EPSON brand scanners are also outlined in this chapter.

Overview 1-1

What Is a Scanner

A scanner is a device that performs the following functions:

❏ Reflects light off your documents ❏ Separates the light by color and intensity ❏ Converts that reflected light to digital data ❏ Sends the digital data to your computer for further processing

Basic scanning principles

A scanner normally includes two components: a light source that illuminates the document and a sensor that detects the light reflected off the document. The sensor is composed of CCD element arrays that detect the brightness of the reflected light and produce corresponding digital signals.

The document is read by a horizontal row of sensors that move vertically down the page. Data from the sensors is read at regular intervals (such as 300 times per inch), achieving very high resolutions.

Data is organized horizontally and vertically; the scanning direction is referred to by the following terms:

1-2 Overview

Main scan

The horizontal scanning direction

Sub scan

The vertical scanning direction

By combining the main scan and sub scan data, an entire page can be converted into organized digital data.

Overview 1-3

Reading color

By illuminating the document with three lights, red (R), green (G), and blue (B), the scanner can analyze and separate a document’s three color components. The computer can then overlay this color-separated data to produce full-color images.

Reading monochrome

Even though you have a color scanner, you can still read your documents as monochrome. Color scanners can read documents as monochrome in two ways:

❏ Treat all the data on the page as the same color. This method uses

all the light sources, and is fine if you plan to print data in black and white only.

❏ Specify one color (R, G, or B) as a dropout color. This method

uses only one light source and reads all data except for the color specified.

1-4 Overview

EPSON Scanner Features

EPSON scanners feature the following special attributes.

❏ A unified control code structure

All scanner features are controlled by EPSON’s ESC/I scanner control codes, so the commands for each feature are the same for all scanner models. All models are downwardly compatible, so programs written for lower level scanners will work identically on upper level scanners.

❏ Internal image data processing circuits

Each scanner contains circuitry capable of processing image data before it is sent to the computer; the type of processing is specified by control codes. By preprocessing image data, the computer can process data faster with a reduction in image distortion.

❏ Support of various interfaces

GT-1000: RS-232C Serial, Bi-directional Parallel GT-4000: RS-232C Serial, Bi-directional Parallel,

SCSI (option)

GT-6000: RS-232C Serial, Bi-directional Parallel,

SCSI (option) GT-8000: Bi-directional Parallel, SCSI GT-6500: RS-232C Serial, Bi-directional Parallel, SCSI GT-8500: Bi-directional Parallel, SCSI GT-9000: Bi-directional Parallel, SCSI GT-300: Bi-directional Parallel, SCSI GT-5000: Bi-directional Parallel, SCSI ES-300C: RS-232C Serial, Bi-directional Parallel,

SCSI (option) ES-600C: Bi-directional Parallel, SCSI ES-800C: Bi-directional Parallel, SCSI ES-1000C: Bi-directional Parallel, SCSI ES-1200C: Bi-directional Parallel, SCSI ES-300GS: Bi-directional Parallel, SCSI Action Scanner II Bi-directional Parallel, SCSI

Overview 1-5

❏ Optional automatic document feeder

An automatic document feeder can be mounted on the GT-8000 (ES-800C), GT-6500 (ES-600C), GT-8500 (ES-1000C), or GT-9000 (ES-1200C) scanner models, allowing you to automatically load and scan multiple documents. This is particularly useful when using OCR (Optical Character Recognition) software to input text from long documents, or when creating an image data base.

❏ Optional transparency illumination unit

This unit can read transparencies (film) when mounted on the GT-8000 (ES-800C), GT-6500 (ES-600C), GT-8500 (ES-1000C), or GT-9000 (ES-1200C) models. You can now scan film directly, without having to first make a print of the film as was necessary in the past. This allows for more accurate reading of film colors with a minimum of degradation in image resolution. You can also now directly read documents stored on film.

1-6 Overview

Control Code Construction

Function level

The EPSON image scanner control language currently has the following function levels: B1 to B5 and A5. The relationship of each level is shown in the following diagram. Each level contains the commands and features of all lower levels.

For example, if you are using a B4-level scanner, all programs made for B1 through B3 levels should run with no problem. All scanners feature the control codes from lower level machines.

However, some scanner settings are unique to particular scanner models, so you must take these into account when writing scanner programs.

Parameters

Some commands require additional parameters. Commands that require parameters do not take effect until the parameters are sent, so always make sure you send the correct parameters. Sending an incorrect parameter may cause a scanner error.

Overview 1-7

Computers and Handshaking

Scanners are connected to their host computers by some kind of interface. Since a scanner sends data to the computer, the interface must carry data not only from the computer to the scanner, but also from the scanner to the computer. For this reason, the interface must be capable of bi-directional communication.

A method of interaction between the computer and scanners is necessary to prevent the computer from sending data at the same time the scanner is sending data. This interaction method is the basis for governing scanner operation.

EPSON scanner and computer interaction is controlled by a method called handshaking. After the computer sends data to the scanner, it must wait for the proper reply from the scanner before sending more data. Also, when the scanner sends data to the computer, it must wait for the correct response from the computer before sending additional data. Handshaking dictates the method of sending data and how the data is acknowledged by both the computer and scanner.

1-8 Overview

Image Data

The manner in which an image is converted into data and the way the data is sent to the computer is predetermined. The following sections describe this process.

Image data format

The smallest element of image data is called a pixel (short for picture element). A pixel is an individual dot; combining these dots, or pixels, forms an image.

If you represent each pixel by one bit of data, you can determine whether that pixel is light or dark (1 or 0). This is called bi-level conversion, and produces bilevel data.

However, most images contain a nearly infinite number of color shades. By increasing the number of data bits per pixel, you can increase the possible number of pixel shades you can represent. As you can see from the following illustration, 1 bit per pixel allows you to show only two shades; 2 bits per pixel allows you to represent up to 4 shades.

The image data format is what determines the amount of data necessary for each pixel. The amount of data determines how many shades you can express. Normally, you can select from 1 to 8 bits per pixel. For monochrome scanning, this data determines the shade of gray. For color scanning, you can differentiate the same number of shades for each of three colors (green, red, and blue).

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As you increase the amount of data, you dramatically increase the number of minute differences in color you can represent.

Bits per pixel Monochrome shades Colors

1 bit/color/pixel 2 8 2 bits/color/pixel 4 64 3 bits/color/pixel 8 512 4 bits/color/pixel 16 4,096 5 bits/color/pixel 32 32,768 6 bits/color/pixel 64 262,144 7 bits/color/pixel 128 2,097,152 8 bits/color/pixel 256 16,777,216

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Line data transfer

The scanner reads one horizontal line of data (main scan) and sends it to the computer. After the computer confirms it has received the data, the scanner sends the next line of data. The scanner repeats theses steps until data for the entire image is sent to the computer. This method is called line data transfer.

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Block data transfer

Line data transfer sends the data to the computer line by line. However, block data transfer sends multiple lines of data to the computer all at once. You can use commands to specify the number of lines sent at one time; in this way you can select the most efficient block size to send your data.

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Functions

EPSON scanners feature a number of various functions. A brief overview of these functions is provided below. For more detailed explanations, see the following chapter on using these functions, as well as the command reference section.

Image definition

Brightness

This function allows you to set the brightness at which images are scanned. The following illustration shows the difference this setting can make in the final scanned image. Setting the brightness to a brighter setting results in a bright image in which some thinner lines may be washed out. On the other hand, setting brightness to a darker setting results in a blacker image in which some intricate details may turn out completely black.

Dark Bright

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Gamma correction

Gamma correction is a function that adjusts the light intensity so it matches the output device.

Although an image may display clearly on your CRT display, your printer may not produce it the same way. Since image reproduction depends on the output device (CRT, printer, etc.), gamma correction adjusts the light intensity so the image is faithfully reproduced on the output device you are using. The term gamma refers to the ratio between the input and output light intensity.

Display A Display B

Printer A Printer B Printer C

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Halftoning

Halftoning adjusts the shade and color of each pixel according to the shade and color of the surrounding pixels. Setting halftoning to large results in a sharper contrast between dots. Setting halftoning to small results in reduced contrast.

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Data form definition

Data format

The data format function determines how many bits are used to represent one pixel. Increasing the bits increases the number of shades and intensity that can be expressed. However, the data required to represent an image is also increased. For example, to scan an A4 size image using 8 bits per pixel at 300 dots per inch (dpi) in color would require 26.4 MB of data.

Also, if your printer or CRT is not capable of expressing these differences in color and shade, there is no reason to produce such precise (and sizable data).

8 bit 2 bit 1 bit

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