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This is an accepted version of this page This is the latest accepted revision, reviewed on 1 February 2025. Lossy compression method for reducing the size of digital images For other uses, see JPEG (disambiguation). "JPG" and "Jpg" redirect here. For other uses, see JPG (disambiguation). JPEG A photo of a European wildcat with the compression rate, and associated losses, decreasing from left ...
Figure 1 shows an edge map, the gradient of the (slightly blurred) edge map, and the GVF field generated by minimizing . Fig. 1. An edge map (left) describes the boundary of an object. The gradient of the (slightly blurred) edge map (center) points towards the boundary, but is very local.
Typically, compressions using lossless operation mode can achieve around 2:1 compression ratio for color images. [5] This mode is quite popular in the medical imaging field, and defined as an option in DNG standard, but otherwise it is not very widely used because of complexity of doing arithmetics on 10, 12, or 14bpp values on typical embedded 32-bit processor and a little resulting gain in ...
Edges extracted from non-trivial images are often hampered by fragmentation, meaning that the edge curves are not connected, missing edge segments as well as false edges not corresponding to interesting phenomena in the image – thus complicating the subsequent task of interpreting the image data. [4]
In MPEG-2, MPEG-4, and AVC, Cb and Cr are taken on midpoint of the left-edge of the 2×2 square. In other words, they have the same horizontal location as the top-left pixel, but is shifted one-half pixel down vertically. Also called "left". [16] In JPEG/JFIF, H.261, and MPEG-1, Cb and Cr are taken at the center of 2×2 the square. In other ...
This process occurs with all beams blanked, and is called the retrace. At the left edge, the field steadily decreases in magnitude to start another forward scan, and soon after the start, the beams unblank to start a new visible scan line. A similar process occurs for the vertical scan, but at the display refresh rate (typically 50 to 75 Hz).
Left side of the image is from a low-quality JPEG image, showing lossy artefacts; the right side is from a PNG image. In information technology , lossy compression or irreversible compression is the class of data compression methods that uses inexact approximations and partial data discarding to represent the content.
Edge detection is a well-developed field on its own within image processing. Region boundaries and edges are closely related, since there is often a sharp adjustment in intensity at the region boundaries. Edge detection techniques have therefore been used as the base of another segmentation technique.