This is an overview of the annual survey series of bibliographies on image engineering in China for the past 25 years. Images are an important medium for human beings to observe the information of the real world around. In its general sense

the word "image" could include all entities that can be visualized by human eyes

such as a still image or picture

a clip of video

as well as graphics

animations

cartoons

charts

drawings

paintings

even also text

etc. Nowadays

with the progress of information science and society

"image" rather than "picture" is used because computers store numerical images of a picture or scene. Image techniques are those techniques that have been invented

designed

implemented

developed

and utilized to treat various types of images for different and specified purposes. They are expanding over wider and wider application areas. They have attracted more and more attention in recent years with the fast advances of mathematic theories and physical principles

as well as the progress of computer and electronic devices

etc. Image engineering (IE) is an integrated discipline/subject comprising the study of all the different branches of image techniques

which has been formally proposed and defined 25 years ago to cover the whole domain. Image engineering

from a perspective more oriented to techniques for treating images

could be referred to as the collection of three related and partially overlapped groups of image techniques

that is

image processing (IP) techniques (in its narrow sense)

image analysis (IA) techniques and image understanding (IU) techniques. In a structural sense

IP

IA and IU build up three inter-connected layers of IE. The three layers follow a progression of increasing abstractness and of decreasing compactness from IP to IA to IU. Each of them operates on different elements (IP's operand is pixel

IA's operand is object

and IU's operand is symbol) and works with altered semantic levels (from low level for IP

via middle level for IA

and to high level for IU). The evolving of image engineering is very quickly

its advances are closely related to the development of biomedical engineering

office automation

industrial inspection

intelligent transportation

remote sensing

surveying and mapping

and telecommunications

etc. To follow the development and to record the progress of image engineering

a bibliography series have been started since the propose of image engineering 25 years ago

and this work has been made consecutively till this year. With a set of carefully selected journals and the thoroughly reading on the papers published

several hundreds of papers related to image engineering are chosen each year for further classification and statistical analysis. The motivations and purposes for this work are three folds. 1) to enable the vast number of scientific and technical personnel engaged in image engineering research and image technology applications for grasping the current status of image engineering research and development

2) to help them for searching relevant literature in a targeted manner

3) to provide useful information for journal editors and authors. Based on these three points

the statistics and analysis of the previous year's literature related to image engineering are carried out in every year. In particular

three works are mainly conducted. 1) Forming a classification scheme for literatures. The coverage of research and technology in image engineering is quite large. For the analysis to be general for the whole domain and specific for particular direction

a classification scheme in two levels for literatures is formed. The top level is for the research domains in general (main-class)

and the bottom level is for the specific research directions (sub-class). With the development of technology

the sub-classes have been adjusted and increased

from the initial 18 sub-classes to the current 23 sub-classes. 2) Analyzing the statistics for main classes of literatures. This analysis could provide a general picture over the different research domains along the years. 3) Analyzing the statistics for sub-classes of literatures. This analysis could deliver a specific figure to the different research directions at the current year. In the past 25 years

a total of 2 964 issues of 15 major Chinese journals on image engineering in China have been selected for this annual survey series. From 65 014 academic research and technical application papers published in these issues

15 850 papers in the field of image engineering have been chosen

and classified according to the contents

into five broad classes: (A) image processing

(B) image analysis

(C) image understanding

(D) technology application and (E) review. Then they are further divided into 23 professional sub-classes

namely in brief: (A1) image capturing; (A2) image reconstruction from projections; (A3) image filtering

transformation

enhancement

restoration; (A4) image and/or video coding; (A5) image safety and security; (A6) image multiple-resolutions; (B1) image segmentation; (B2) representation

description

and measurement of objects; (B3) analysis of color

shape

texture

structure

motion

spatial relation; (B4) object extraction

tracking

and recognition; (B5) human biometrics (face

organ

etc.) identification; (C1) image registration

matching and fusion; (C2) 3-D modeling and real world/scene recovery; (C3) image perception

interpretation and reasoning; (C4) content-based image and video retrieval; (C5) spatial-temporal technology; (D1) system and hardware; (D2) telecommunication application; (D3) document application; (D4) bio-medical imaging and applications; (D5) remote sensing

radar

surveying and mapping; (D6) other application domains; and (E1) cross category summary and survey. In this paper

these classified data for all 25 years are integrated and analyzed. The foremost intention is to show a progression of image engineering

and to provide a vivid current picture of image engineering. An overview of the literature survey series on image engineering made in the last 25 years is supplied. The idea behind as well as a thorough summary of obtained statistics for this survey are illustrated and discussed. Many useful information regarding the tendency of fast progresses of image engineering can be obtained. According to the statistics collected and analyses performed

it is seen that the field of image engineering has changed enormously in recent years. It is seen that techniques for image engineering being developed

implemented and utilized on a large scale no one would have predicted a few years ago. One interesting point should be mentioned here is that the fast growth and relative increase of image analysis publications over image processing publications are clearly observed. This gives an indication of a general tendency for the image engineering toward to higher layer. After image analysis

image understanding will catch up and come from behind. This trend has already made an appearance

for example

in the International Conference on Image Processing (ICIP 2017)

the new research papers related to topic of "Image

&

Video Interpretation

&

Understanding" are much more than those related to topic of "Image

&

Video Analysis" (

http://2017.ieeeicip.org/

http://2017.ieeeicip.org/

). In addition to the statistical information for publication in these 25 years

some main research directions are analyzed and deliberated

especially those in image processing

image analysis and image understanding

to present more comprehensive and credible information on the development trends of each technique class. Some insights from it are also pointed and discussed. It is evident that through the statistical analysis of the published papers in important journals of image engineering

it cannot only help people understand the general situation of researches and applications

but also provide scientific basis for the development of relevant disciplines and research strategies.