انتخاب اتوماتیک تصویر مرجع در تطبیق هیستوگرام
محورهای موضوعی : مهندسی برق و کامپیوترنجمه صمدیانی 1 * , حمید حسن‌پور 2
1 - دانشگاه شاهرود
2 - دانشگاه صنعتی شاهرود
کلید واژه: بهبود کنتراست تطبيق هيستوگرام برابرسازي هيستوگرام معيار شباهت,
چکیده مقاله :
در اين مقاله روشي براي انتخاب اتوماتيک تصوير مرجع در تطبيق هيستوگرام ارائه شده است. تطبيق هيستوگرام يکي از ساده‌ترين روش‌هاي مکاني بهبود تصوير است که با توجه به هيستوگرام تصوير مرجع، کنتراست تصوير اوليه را بهبود مي‌دهد. در روش‌هاي معمول تطبيق هيستوگرام، کاربر براي يافتن مناسب‌ترين تصوير مرجعي که بهتر از ساير تصاوير هدف، کنتراست تصوير را بهبود ببخشد، نيازمند انجام چندين آزمايش با عکس‌هاي گوناگون روي تصوير اوليه است اما اين مقاله، روشي براي انتخاب اتوماتيک تصوير مرجع در تطبيق هيستوگرام ارائه مي‌دهد. روش کار بدين صورت است که براي تجزیه مؤلفه روشنایی از رنگ، ابتدا تصاوير از فضاي رنگي RGB به فضاي HSV انتقال مي‌يابند. سپس تصوير مرجع مناسب براي بهبود تصوير اوليه، توسط يک معيار شباهت با سنجش ميزان شباهت بين هيستوگرام مؤلفه روشنایی تصاوير موجود در پايگاه داده و هيستوگرام مؤلفه روشنایی تصوير اوليه انتخاب مي‌شود. به عبارت ديگر، تصويري که هيستوگرام آن شباهت بيشتري به هيستوگرام تصوير اوليه دارد در بهبود کنتراست تصوير اوليه، موفق‌تر عمل مي‌کند. انجام اين کار علاوه بر به دست آوردن نتيجه مطلوب، کاربر را از دغدغه انتخاب يک تصوير مرجع مناسب براي بهبود تصوير اوليه نيز بي‌نياز مي‌کند. همچنين روش ارائه‌شده قابل استفاده روي تصاوير هر دو حوزه RGB و خاکستري نيز مي‌باشد.
In this paper, a method is proposed to automatically select reference image in histogram matching. Histogram matching is one of the simplest spatial image enhancement methods which improves contrast of the initial image based on histogram of the reference image. In the conventional histogram matching methods, user should perform several experiments on various images to find a suitable reference image. This paper presents a new method to automatically select the reference image. In this method, images are converted from RGB to HSV, and the illumination (V) components are considered to select the reference image. The appropriate reference image is selected using a similarity measure via measuring the similarity between the histograms of the initial image and histograms of the images in the data base. Indeed, an image with similar histogram to the histogram of the original images is more appropriate to choose as the reference image for histogram matching. Results in this research indicate superiority of the proposed approach, compared to other existing approaches, in image enhancement via histogram matching. In addition, the user would have no concern in selecting an appropriate reference image for histogram matching in the proposed approach. This approach is applicable to both RGB and gray scale images.
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