Quadtrees, transforms and image coding

Transforms and quadtrees are both methods of representing information in an image in terms of the presence of information at differing length scales. This paper presents a mathematical relationship between these two approaches to describing images in the particular case when Walsh transforms are used. Furthermore, both methods have been used for the compression of images for transmission. This paper notes that under certain circumstances, quadtree compression produces identical results to Walsh transform coding, but requires less computational effort to do so. Remarks are also made about the differences between these approaches

Quadtrees, transforms and image coding

Transforms and quadtrees are both methods of representing information in an image in terms of the presence of information at differing length scales. This paper presents a mathematical relationship between these two approaches to describing images in the particular case when Walsh transforms are used. Furthermore, both methods have been used for the compression of images for transmission. This paper notes that under certain circumstances, quadtree compression produces identical results to Walsh transform coding, but requires less computational effort to do so. Remarks are also made about the differences between these approaches

Kompresi Citra Digital dengan menggunakan Metode Quadro, Discrete Wavelet Transform (DWT) dan Run Length Encoding (RLE)

ABSTRAKSI: Kompresi citra digital merupakan salah satu metoda dalam pengolahan citra yang berfungsi untuk mengurangi ukuran data citra murni yang besar dengan cara mengurangi informasi (lossy) atau tetap mempertahankannya (lossless). Pada tugas akhir ini dikembangkan suatu metode kompresi citra digital yang menggabungkan Quadro,Discrete Wavelet Transform (DWT) dan Run Length Encoding (RLE). Penerapan prinsip segmentasi citra dalam penghentian Quadro dan dilanjutkan dengan metode DWT yang menghasilkan citra dengan kombinasi nilai intensitas yang jauh lebih sederhana dengan hanya mengambil nilai pentingnya saja (subband LL). Hanya nilai penting ini yang kemudian digunakan pada proses inverse DWT (IDWT) dan dilanjutkan dengan proses threshold untuk mendapatkan keseragaman nilai pada pixel-pixel tetangga. Sehingga akan menghasilkan nilai rasio kompresi yang lebih besar setelah proses RLE.Kata Kunci : Quadro, DWT, Threshold, RLEABSTRACT: Digital image compression is one of method that used in image processing to reduce storage size of image by reduce it information (lossy) or remain to maintain it (lossless). In this final task, the digital image compression has developed by combining methods of Quadro, Discrete Wavelet Transform (DWT) and Run Length Encoding (RLE). Using the image segmentation in stopping the Quadro and then continued by implemented the DWT method which would result a simpler combination value of image’s color intensity with only saving the important value of an image (in subband LL). Then, using only this important value but zero-ing others subband, the process continued to the inverse of DWT and then threshold method to get homogeneous values within the neighbor pixels. Thus, it will end with greater value of compression ratio which is done by the RLE.Keyword: Quadro, DWT, Threshold, RL

Quadtrees, Transforms and Image Coding

Transforms and quadtrees are both methods of representing information in an image in terms of the presence of information at di#ering length scales. This paper presents a mathematical relationship between these two approaches to describing images in the particular case when Walsh transforms are used. Furthermore, both methods have been used for the compression of images for transmission. This paper notes that under certain circumstances, quadtree compression produces identical results to Walsh transform coding, but requires less computational e#ort to do so