8-bit Grayscale Research Articles

A database for handwritten text recognition research

An image database for handwritten text recognition research is described. Digital images of approximately 5000 city names, 5000 state names, 10000 ZIP Codes, and 50000 alphanumeric characters are included. Each image was scanned from mail in a working post office at 300 pixels/in in 8-bit gray scale on a high-quality flat bed digitizer. The data were unconstrained for the writer, style, and method of preparation. These characteristics help overcome the limitations of earlier databases that contained only isolated characters or were prepared in a laboratory setting under prescribed circumstances. Also, the database is divided into explicit training and testing sets to facilitate the sharing of results among researchers as well as performance comparisons.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Graphic file compression on a Macintosh.

AutoDoubler, Compact Pro, DiskDoubler, StuffIt Deluxe, and StuffIt SpaceSaver compression applications for the Macintosh were tested for size of compressed files, and time to compress and expand. EPS, TIFF, PICT and Photoshop native format file types were used, in 1-bit, 8-bit greyscale, 8-bit colour (indexed), 24-bit colour (red, blue, green (RGB)), and 32-bit colour (cyan, magenta, yellow, black (CMYK)) modes. JPEG compression is illustrated by comparing an uncompressed image with three images compressed at different rates.

Optimized algorithms for displaying 16-bit gray scale images on 8-bit computer graphic systems.

Most personal computers contain 8-bit graphic display hardware, whereas most medical gray scale images are stored at 16-bit per pixel integers. To display medical gray scale images on such computers, the 16-bit image data must be remapped into 8-bit gray scale images. This report presents the algorithms and computer code that allow very rapid 16-bit to 8-bit image data transformation. These algorithms are helpful in allowing personal computers with at least the performance of a Macintosh II (Apple Computer, Cupertino, CA) computer to function as low-end picture archiving communication systems or personal workstations.

Comparison of 12-Bit and 8-Bit Gray Scale Resolution in MR Imaging of the CNS

Comparison of 12-Bit and 8-Bit Gray Scale Resolution in MR Imaging of the CNS

Comparison of 12-Bit and 8-Bit Gray Scale Resolution in Mr Imaging of the CNS

A reduction in gray scale resolution of digital images from 12 to 8 bits per pixel usually means halving the storage space needed for the images. Theoretically, important diagnostic information may be lost in the process. We compared the sensitivity and specificity achieved by 4 radiologists in reading laser-printed films of original 12-bit MR images and cathode ray tube displays of the same images which had been compressed to 8 bits per pixel using a specially developed computer program. Receiver operating characteristic (ROC) curves showed no significant differences between film reading and screen reading. A paired 2-tailed t-test, applied on the data for actually positive cases, showed that the combined, average performance of the reviewers was significantly better at screen reading than at film reading. No such differences were found for actually negative cases. Some individual differences were found, but it is concluded that gray scale resolution of MR images may be reduced from 12 to 8 bits per pixel without any significant reduction in diagnostic information.

Comparison of 12-Bit and 8-Bit Gray Scale Resolution in MR Imaging of the CNS

Comparison of 12-Bit and 8-Bit Gray Scale Resolution in MR Imaging of the CNS

Secondary Ion Imaging with a CCD Camera

AbstractA digital image processing system based on a charge-coupled device (CCD) camera interfaced to a Texas Instruments Professional Computer (TIPC) has been implemented on the Cameca IMS-3F Ion Microscope to improve lateral imaging capabilities. The CCD sensor, produced at TI, generates a 376 × 288 pixel image, and a hardware interface to the TIPC provides an 8-bit grayscale (256 levels) for subsequent storage and display. The Cameca ion microscope projects secondary ions from the sample onto a microchannel plate/fluorescent screen combination. The CCD array images the screen directly and no vacuum modifications to the Cameca are required. Nitrogen cooling of the CCD imager to reduce thermal noise allows low light levels to be integrated for several minutes and displayed on the TIPC, providing a substantial increase in sensitivity over the standard optics. False color imaging enhances the contrast of various features in the ion image to provide ease of identification. A variety of software options, such as frame mosaicking, multiple frame overlays, color threshold modification and histogram equalization are available. The TIPC has also been interfaced to the Cameca controlling computer to allow display of ion images during depth profiling.