![]() If these TIFF files are loaded into Photoshop only the first image will be visible. Some applications (like for example nona, the PTStitcher replacement in the hugin package) can write single files that contain multiple TIFF images. ZIP usually results in smaller files, smaller even as if saved as PSD (where you can't choose the compression format). This separate TIFF tag can be compressed using RLE (run length encoding) or ZIP compression. If a Photoshop document with layers is saved as TIFF Photoshop creates a flat TIFF image file (for compatibility) and the layer data in a separate TIFF tag. Erik Krause provides a Photoshop action set on his page that can be used to automate this for all images in a panorama: Stitching actions Layers This can be achieved manually by loading the alpha channel as selection and creating a mask with 'reveal selection'. It loads the alpha channel but doesn't use it to control transparency. In any case there is a problem to use this alpha channels as intended in Photoshop, since Photoshop does not know about the intended use. See PTStitcher sample script on Jim Watters page for details: There is a 'feather' parameter to control the width of a grayscale gradient to allow for smooth blending between the images. For the 'with feather' (TIFF_mask) output the mask is calculated to give a seam between adjacent images that lies more or less in the middle of the overlap area.If the output type 'without feather' (TIFF_m) is used, a mask is created that reflects the remapped input image borders.A mask in the source image is treated as image border and remapped to the output image accordingly. ![]() PTStitcher, the main stitching application of the Panorama Tools, is capable of reading and writing masked TIFF image files in RGB color space. This is particularily useful to blend between images. A alpha channel pixel with 50% gray indicates 50% transparency. For this purpose the alpha channel contains a black-and-white image where the pixel value determines the transparency of the corresponding image pixel.Ī white alpha channel pixel causes the corresponding image pixel to be seen to 100%, a black alpha channel pixel indicates a totally transparent image pixel. ![]() A mask contains information to which extent the image should be used. Details see Full 16 bit workflow Alpha channels and masksĪlpha channels are used by panotools to store masks. The Panotools main applications process 8-bit as well as 16-bit per channel images. any number of additional channels (called alpha channels) specifying masks, selections, additional color channels or what ever.Īll channels in an image have the same bit depth, hence a RGB image with 16-bit per channel often is reffered to as a 48-bit image, with 8-bit per channel as a 24-bit image.four channels specifying a color image in CMYK color space.three channels specifying a color image in RGB color space.a single channel specifying a black-and-white image.However, there is a specification that contains 32-bit data per channel floating point format for high dynamic range images. TIFF can contain data of varying bit depth but for photographic purpose only 8-bit or 16-bit per channel are of interest. See opening large TIFFs with Photoshop for details. ![]() There is a bug in Photoshop prior to Version 9 (CS2) that prevents to open PackBits compressed files beyond a certain size. PTStitcher (and hence all the GUI front-ends that use it) outputs PackBits compressed image files if the output format is TIFF.
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