When you autoscale, it resets the display range to match the data range, making values 67 and below appear black, values 520 and above appear white, and everything in between scaled linearly. So all those values (57 to 520) will appear near black. 67 to 520, but stored as a 16-bit image (with potential values ranging from 0 to 65535), the default display range is also 0=black, 65535=white, and values in between scaled linearly. If your image has intensity values ranging from e.g. In other words, it is unlikely that your image is actually all 0 values, but rather the display range is probably not set to align with the data range. You can verify whether the actual data is there by moving the mouse over the image, and looking at the pixel probe output in the status bar area of the main ImageJ window. You can fix this by clicking on Image ▶ Adjust ▶ Brightness/Contrast. For example, on a 12-bit camera, the largest possible intensity value is 4095-but with 0 mapped to black and 65535 mapped to white, 4095 ends up (linearly) mapped to a very very dark gray, nearly invisible to the human eye. In that case, the display is scaled to the full 16-bit range (0 - 65535 intensity values), even though the actual data values typically span a much smaller range. This problem can arise when 12-bit, 14-bit or 16-bit images are loaded into ImageJ without autoscaling. For more information about the CMYK, RGB, HSB, and grayscale color models, see Understanding color models.From the ImageJ wiki's Troubleshooting page: For this reason, you should finish editing and then save an image before you convert it to a new color mode.Ĭolor modes are based on standard color models used to describe, classify, and reproduce color digitally. For the same image dimensions, a CMYK image has a larger file size than an RGB image, but it contains the channels necessary to print standard inks.Įach time you convert an image, you may lose color information. Colors from the RGB color space can cover a greater range of the visual spectrum (they have a larger gamut) than those from the CMYK color space. Each channel has a bit depth of 8 bits.Īlthough on the screen you may not be able to see the difference between an image in the CMYK color mode and an image in the RGB color mode, the images are quite different. Similarly, the CMYK (32-bit) color mode is composed of cyan, magenta, yellow, and black channels and has a bit depth of 32 bits. For example, the RGB (24-bit) color mode is composed of red, green, and blue channels and has a bit depth of 24 bits. For the World Wide Web, photos should be in the RGB color mode and GIF images should be in the paletted color mode.Ĭolor modes are described by their component colors and bit depth. For example, it is recommended that images sent for high-end printing be in the CMYK color mode. You can convert images to different color modes, depending on their intended use. Computer monitors display images in the RGB color mode images in Corel PHOTO-PAINT are created in the RGB color mode by default. In Corel PHOTO-PAINT, the colors of images are defined by color modes.
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