Digital Image Processing #HW1 -Extraction of Bitmap Header File -Manipulation of Image Pixel Information Contact Information Tzu-Jui Wang ( 王子睿 ) Visual Communications Lab Dep. of Communications Engineering, National Central University No.300, Jhongda Rd., Jhongli City, Taoyuan County 32001, Taiwan (R.O.C.) Phone:

Outline Reference Work Flow Introduction to Bitmap File Homework Details – Extract Header File – Construct Histogram – Extract Region of Interest with Specified Coordinate Set Grading Policy Demo Schedule

Reference A Beginners Guide To Bitmaps, – bitmaps/ bitmaps/ – Data type in Computer, wiki resources, – ce) ce) Those might be useful !

Work Flow Extract region of interest Input coordinate set (x i, y i ), i=1,..,4 of bounding box (x 1,y 1 )(x 2,y 2 ) (x 3,y 4 )(x 4,y 4 ) Extract header information Construct histogram on R, G, B channels, respectively Extract pixel information 24-bit8-bit

Introduction to Bitmap File (1/2) Bitmap File Header Identifier (ID)2 File Size4 Reserved4 Bitmap Data Offset4 Bitmap Info Header Bitmap Header Size4 Width4 Height4 Planes2 Bits Per Pixel2 Compression4 Bitmap Data Size4 H-Resolution4 V-Resolution4 Used Colors4 Important Colors4 Color Table (Palette) PaletteN*4 Bitmap Array Bitmap DataN/A File header (14 bytes) Info header (50 bytes) Header file (Image profile) Image content Pixel information i.e. a 8-bit image, N = 2 8 Empty for 24-bit image

Introduction to Bitmap File (2/2) Header + Color palette Header 54 bytes 54 bytes bytes Image content 24-bit lena.bmp 8-bit lena.bmp

Construct Histogram Histogram on R, G, B channels Figure1: beatles.bmpFigure2: RGB histogram Frequency Pixel value

Extract Region of Interest with Specified Coordinate Set Suppose given (x 1, y 1 ), (x 2, y 2 ), (x 3, y 3 ), (x 4, y 4 ) – The bounding box will be as followed (x 1,y 1 ) (x 2,y 2 ) (x 3,y 3 ) (x 4,y 4 ) Bounding box Final output

Grading Policy – Code & Demo (80%) Everyone will be asked few questions. Extract Header File (20%) – We’ll test your system with images except lovely Lena. Construct Histogram (30%) – Same as the above. Extract Region of Interest with Specified Coordinate Set (30%) – Arbitrarily give four coordinates, and create a new bitmap file with extracted region.

Grading Policy – Report (20%) Report (20%) – Plot all your experimental results. (10%) – Depict the.bmp format as clear as possible. (5%) – Describe your findings as rich as possible. (5%) We don’t force you to write down how you feel about this homework. But, you can still show it up. – Too trivial, too hard, …too ? – You can describe any difficulty you’ve encountered.

Demo Time Demo time will be at , begin around 7:00 pm (2 weeks later) at R3-307 (VCLab). Demo orders will be announced later, 5 minutes for each, please refer TA’s website. – tml tml – Bring your codes and report. – No delay is allowed except a special cause.