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We have developed a reversible method to convert color graphics and pictures to gray images. The method is based on mapping colors to low-visibility high-frequency textures that are applied onto the gray image. After receiving a monochrome textured image, the decoder can identify the textures and recover the color information. More specifically, the image is textured by carrying a subband (wavelet) transform and replacing bandpass subbands by the chrominance signals. The low-pass subband is the same as that of the luminance signal. The decoder performs a wavelet transform on the received gray image and recovers the chrominance channels. The intent is to print color images with black and white printers and to be able to recover the color information afterwards. Registration problems are discussed and examples are presented.

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Abstract— A technique was developed and tested for generating CRT pictorial image reproductions that match the color appearance of print originals. Five observers, experienced in using Adobe Photoshop™ to adjust images, matched two scenes using a memory‐matching technique. Observers were able to produce accurate matches when originals and reproductions were viewed at the same white point. Observers then matched the reproductions at 6500 K to originals viewed at 9300 and 3000 K. These matches were compared to the predictions of various color‐appearance models, using a paired‐comparison technique in a psychophysical experiment using different observers. The observer‐matched images were found to be equal or superior to matches produced using any of the models.

Biological invasions have important ecological impacts at both local and global levels, affecting biodiversity, ecosystem functioning, and economic sustainability. The study of invasions requires specific methodological approaches to gain rapid insight into the spatial and temporal dynamics of the system. We studied a recent invasion by the exotic herb Hieracium pilosella L. (Mouse-ear hawkweed, Asteraceae) in the Argentinean portion of the northern part of Tierra del Fuego Island in Southern Patagonia. To assess the extent of this invasion and the related ecological and land use factors, we performed an extensive field sampling at a regional scale and used a spatial pattern approach using geostatistical techniques to build a map of the invasion. Our results showed that the invading species is widely distributed across the entire Fuegian steppe, in general with low cover (\2%) and a particular spatial structure having hot spots (10-70%) related to specific land uses. We found regionallatitudinal and also local-community level variability in the frequency, cover and spatial distribution of the invasive species, each of them associated with particular ecological factors, and no association with regular domestic animal grazing. Region-wide invasion may be accounted for by wind dispersal of the seeds and the latitudinal variability of the precipitation; while localvariability was associated with the susceptibility of different plant communities to invasion. Hot spots were found to be related to massive soil disturbances (e.g., road building, shrub removal, physical impacts of long-term and intense domestic animal use, etc.), probably due to the presence of bare soil favoring colonization by the invading species. Scrublands, lawns and grasslands were more invaded than wetlands, heathlands or salt grasslands. Since the invasion is apparently at initial stages due to the low cover values found, we believe that information about the extent and environmental or management factors involved in this exotic plant's expansion should be used to design appropriate control and mitigation tools. In this sense, our results point to management actions focused on reducing the presence of hot spots of invasion by means of quick revegetation of bare soil after a massive disturbance event takes place.