evaluation techniques on tiff image for better ...

EVALUATION TECHNIQUES ON TIFF IMAGE FOR BETTER FORECASTING OF SATELLITE IMAGES Rutvij Jhaveri1, Trupti Manik2, Viral Kapdia3 1

Department of Computer Engineering and Information Technology, SVMIT, Bharuch (India)

2

Department of Computer Engineering and Information Technology, SVMIT, Bharuch (India) 3

Department of Computer Engineering, BVM, Vallabh Vidyanagar (India)

Abstract-TIFF-Tagged Image File Format is mainly used for bitmap data. The purpose of TIFF is to describe, store and interchange raster image data. A main goal of TIFF is to provide a well-heeled environment within which applications can exchange image data. We have thoroughly studied the TIFF image and through implementation of various techniques of evaluation we found that this paper would be a great aid for scientists working on forecasting and evaluation of satellite images. This subject will gain more popularity in future. Keywords- TIFF, IFD, Color Selection, Crop, Rotate

I. INTRODUCTION TIFF is an image file format. The maximum possible length of a TIFF file is 2**32 bytes. In this paper, a file is defined to be a series of 8-bit bytes. The bytes are numbered from 0 to N. At the beginning of a TIFF file, there is an 8-byte image file header pointing to an Image File Directory. An Image File Directory (IFD) contains information of the image and pointers to the actual image data. The programmer needs an uncomplicated way of obtaining image data in a standard working format. TIFF is designed to encourage the exchange of digital image information. It can portray bi-level, grayscale, palette-color, and full-color image data in several color spaces. This paper depicts various evaluation techniques like color selection, crop and rotate on TIFF image. II. FILE STRUCTURE OF TIFF

TABLE 1 TIFF IMAGE FILE HEADER

Offset Data Type

Value

0

Word

Byte order indication

2

Word

Version number (always 42)

4

Unsigned Long Offset to first IFD

B. IMAGE FILE DIRECTORY IFD can be located anywhere in the file. Every 'page' in a multi-page TIFF is represented by exactly one IFD. Here's a more detailed view of this IFD. The tags in this IFD should be sorted by code. Every tag takes up exactly 12 bytes (Table-2). Data type of the tag data (Table3) is the data type of the basic building block of this tag data. If the tag data is an array of bytes, this data type would be byte. The tag data length describes the size of this data type, multiplied by number of values. If this data length is smaller than or equal to 4 bytes, the actual tag data is included in the IFD, at offset 8 from the beginning of the tag structure. Otherwise, the tag data is stored in any other location within the TIFF file, and a pointer to that location, from the beginning of the file, is written at offset 8 from the beginning of the tag structure. In other words, if the tag data is smaller than or equal to 4 bytes, it fits. Otherwise, it is stored elsewhere. TABLE 2 STRUCTURE OF IFD

File structure of TIFF has three parts: File Header, Image File Directories and Data. A. IMAGE FILE HEADER In TIFF, Header gives certain useful information. From header one can know the byte order that is either II or MM. Next 2 bytes indicate a specific constant number 42 which indicates that file is a TIFF file. Next four bytes shows offset of first IFD (Table-1).

Offset

Data Type

Value

0

Word

Number of tags in IFD

2+x*12

Tag structure Tag data

2+(number of tags in Unsigned IFD)*12 Long

Offset to next IFD, if there is a next IFD 0 otherwise

IV. APPLICATION DESCRIPTION

TABLE 3 TIFF TAG STRUCTURE

A. Flow of Application Offset Data Type

Value

0

Word

Tag identifying code

2

Word

Data type of tag data

4

Unsigned Long

Number of values

8

x * Tag-data data type Tag or Unsigned Long offset or offset see below see below

to

Table 4 describes the complete description of application, and application flow is shown in Fig. 2. B. Coding Standards

tag

data data

III. ACTIVITY DIAGRAM Activity diagram (Fig. 1) indicates the flow of the process. First of all, image is selected and opened. Thereafter, operation is selected, which is to be performed on the image. Operations include color selection, crop and rotate. Any of the operation can be performed on TIFF image regardless of the sequence of operation.

Following coding standards are used while developing the application:  Variables are given natural and understandable name according to the task.  Function is used whenever it is required, and each function name is related to the task it is performing.  Variables are declared in the consistent manner. TABLE 4 DESCRIPTION OF APPLICATION

Option

Description

File

This option enables to open and save the selected file. This option enables to view file in different modes like Scale to fit, Stretch to fit and Actual size. This option enables to analyze the image. The user can calculate NDVI that is Normalized Difference Vegetative Index. User can also Filter the pixels of the image. Third option is the Band Math that facilitates to perform various band arithmetic operations on the image. This Option enables the user to evaluate the image. User can perform color selection on the image in which user can alter the bands of the image. This option also enables to crop and rotate the image. Image can be cropped from desired location and can be cropped in desired size.

View Analysis

Evaluation

Fig. 1 Activity Diagram

Fig. 2 Application Flow

V. MULTIBAND IMAGE EVALUATION

Fig. 5 Specifying band numbers for Color Selection

Fig. 3 A multiband image We have evaluated a multiband image (Fig. 3) with three options: Color Selection, Crop and Rotate. A. Color Selection The above shown image is a 3 band image. In color selection, we can alter the color of the bands. By selecting this option user can alter the Red, Green and Blue Band. Clicking on Color Selection below window is displayed which asks for specifying the band numbers (Fig. 4).

Fig. 4 Specifying band numbers for Color Selection

We have assigned band 2 to Red, 3 to Green and 1 to Blue band respectively. After color selection, the bands of the image get altered and the image is displayed (Fig. 5). B. Crop On selecting Crop option a new window is opened. This window asks for four values to be specified. We have entered coordinates X=0 and Y=0 and width=300 and height=300 for the image (Fig. 6). After specifying the coordinates, image is cropped according to specified dimensions(Fig. 7).

Fig. 6 Image before crop

VI. CONCLUSIONS In this paper, we have portrayed foundation for image processing on .tiff image file. Using various evaluation techniques like color selection, crop and rotate, a TIFF image can be thoroughly studied. Scientists working on GIS image processing would find this as a source of acquaintance. We would like to highlight that our approach would be able to serve as a general outline for a variety of GIS evaluation tasks. VII. ACKNOWLEDGEMENTS Bhaskaracharya Institute for Space Applications and GeoInformatics (BISAG) has greatly supported our work. Due to their help and support during the implementation, we have completed our implementation successfully. Any findings, views and conclusions or recommendations articulated in this paper are those of the authors and do not necessarily reflect the views of BISAG.

Fig. 7Image after Crop operation

REFERENCES [1] Paul Bourke. TIFF Image Creation, August 1998.

B. Rotate This option enables to rotate the image in 90, 180 and 270 degrees. We have rotated image (Fig.3) by 90 degrees and the resulting image is displayed (Fig. 8).

[2] TIFF Revision 6.0. June, 1992. partners.adobe.com/public/developer/en/tiff/TIFF6.pdf [3] Digital Image Manipulation http://radiographics.rsna.org/content/23/5/1338.short [4] G. Parsons, J. Rafferty. Tag Image File Format (TIFF) - F Profile for Facsimile, March 1998. [5] Noboru Otaki. Colour image evaluation systems [6] Alexander Wilkie, Robert F. Tobler and Werner Purgathofer. A spectral extension to the Tagged Image File Format. [7] Jessica Hill Robin. Improving predictive capabilities of environmental change with globe data.

Fig. 8 Image after Rotate operation.