Piece-wise Linear Transformation is type of gray level transformation that is used for image enhancement. It is a spatial domain method. It is used for manipulation of an image so that the result is more suitable than the original for a specific application.
Some commonly used piece-wise linear transformations are:
Low contrast image occur often due to improper illumination or non-linearly or small dynamic range of an imaging sensor. It increases the dynamic range of grey levels in the image.
Contrast Stretching Transform is given by:
S = l.r, 0 <= r < a S = m.(r-a) + v, a <= r < b S = n.(r-b) + w, b <= r < L-1 where l, m, n are slopes
A special case of contrast stretching is clipping where l=n=0. It is used for noise reduction when the input signal is known. It puts all grey levels below r1 to black(0) and above r2 to white(1).
Another special case of contrast stretching is thresholding where l=m=t. It is also used for noise reduction. It preserves the grey levels beyond r1.
Grey level slicing:
Highlighting a specific range of grey level in an image.
- To display a high value for all grey levels in the range of interest.
- To display a low value for all grey levels.
- Brighten the desired range og grey level.
- Preserve the background quality in the range.
An 8-bit image can be represented in the form of bit plane. Each plane represents one bit of all pixel values. Bit plane 7 contains the most significant bit (MSB) and bit plane 0 contains least significant bit (LSB). The 4 MSB planes contains most of visually significant data. This technique is useful for image compression and steganography.
- 2D Transformation in Computer Graphics | Set 1 (Scaling of Objects)
- 2D Transformation | Rotation of objects
- Window to Viewport Transformation in Computer Graphics with Implementation
- Python | Intensity Transformation Operations on Images
- Perspective Transformation - Python OpenCV
- Log transformation of an image using Python and OpenCV
- Python OpenCV - Affine Transformation
- Overview of Data Structures | Set 1 (Linear Data Structures)
- Human Resource Management (HRM)
- Draw a triangle in C++ graphics
- Python - Displaying real time FPS at which webcam/video file is processed using OpenCV
- Difference between Multimedia and Animation
- How to Convert images to NumPy array?
- Various kinds of Aspect Ratios
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to firstname.lastname@example.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.