alpha

问题 I have RGB color value and alpha value. How can I get new RGB value assuming that I have white backgound and alpha is applied? 回答1: The formula to be applied to each of the color channels is the following: cr = cf * af + cb * ab * (1 - af) where cr is the resulting color of the pixel, cf is the foreground color, cb the background color, af foreground alpha and ab background alpha. Note that often color values are stored already premultiplied by alpha in which case the formula simplifies to cr

问题 I have RGB color value and alpha value. How can I get new RGB value assuming that I have white backgound and alpha is applied? 回答1: The formula to be applied to each of the color channels is the following: cr = cf * af + cb * ab * (1 - af) where cr is the resulting color of the pixel, cf is the foreground color, cb the background color, af foreground alpha and ab background alpha. Note that often color values are stored already premultiplied by alpha in which case the formula simplifies to cr

问题 I am using this code snippet to load various image files: BitmapImage bitmap = new BitmapImage (); bitmap.BeginInit (); bitmap.UriSource = new System.Uri (path); bitmap.CreateOptions = BitmapCreateOptions.PreservePixelFormat; bitmap.EndInit (); This works fine for TIFF files stored as RGB, RGB+Alpha and CMYK. However, if I try to load a TIFF file using CMYK colors and an alpha channel, I get an exception (the file format is not recognized as being valid by the decoder). I was previously using

问题 I am using this code snippet to load various image files: BitmapImage bitmap = new BitmapImage (); bitmap.BeginInit (); bitmap.UriSource = new System.Uri (path); bitmap.CreateOptions = BitmapCreateOptions.PreservePixelFormat; bitmap.EndInit (); This works fine for TIFF files stored as RGB, RGB+Alpha and CMYK. However, if I try to load a TIFF file using CMYK colors and an alpha channel, I get an exception (the file format is not recognized as being valid by the decoder). I was previously using

问题 I am working on a handwriting application on iOS. I found the sample project "GLPaint" from iOS documentation which is implemented by OpenGL ES, and I did something modification on it. I track the touch points and calculate the curves between the points and draw particle images alone the curve to make it looks like where the finger passby. glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE,

问题 I am working on a handwriting application on iOS. I found the sample project "GLPaint" from iOS documentation which is implemented by OpenGL ES, and I did something modification on it. I track the touch points and calculate the curves between the points and draw particle images alone the curve to make it looks like where the finger passby. glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE,

问题 I have a jpeg containing alpha blended text. Knowing the font and size, I deduced a png file representing the text Using ImageMagick, can I get an approximation of the original picture? 回答1: Albert Myšák has the proper technique here, since one knows the exact alpha channel values for the text and the equation that describes how the alpha channel is blended with the image. Kudos! My earlier methods are better suited to when one only knows the positions of the text pixels in the image, so that

问题 I need to create a surface that has a bounding circle. Anything drawn on that surface should not be visible outside that bounding circle. I've tried using masks, subsurfaces, srcalpha, etc., but nothing seems to work. My attempt: w = ss.get_width () h = ss.get_height () TRANSPARENT = (255, 255, 255, 0) OPAQUE = ( 0, 0, 0, 225) crop = pygame.Surface ((w, h), pygame.SRCALPHA, ss) crop.fill (TRANSPARENT) c = round (w / 2), round (h / 2) r = 1 pygame.gfxdraw. aacircle (crop, *c, r, OPAQUE) pygame

问题 Q : Is there a way to use the default pipeline to blend the Alpha component properly? Problem : I'm drawing semi-transparent surfaces into a texture, then I want to blit that texture into the main frame back buffer. Normally when you use straightforward alpha blending for transparency or antialiasing, it is to blend color components into the back buffer ( which has no alpha channel by deafult ). However, when blending into a texture that has an alpha component, the usual GL_SRC_ALPHA, GL_ONE

问题 This question already has answers here : How can I make an Image with a transparent Backround in Pygame? (2 answers) How do I blit a PNG with some transparency onto a surface in Pygame? [duplicate] (4 answers) pygame image background does not match main background (1 answer) How to make a surface with a transparent background in pygame (3 answers) Closed 3 months ago . I have read the top 20 posts relating to this issue here, read many examples on Google, tried using .convert() , .convert