jpeg

问题 I am trying to build an uploader which uploads progressive files in two steps: Upload the minimal number of bytes to create a thumbnail (0-10%) Upload the rest of the bytes for the thumbnail. (11%-100%) I want to do this to have thumbnails available earlier without having to upload a seperate thumbnail. Taking an image (3426398 Byte) which was created with jpegtran -copy all -progressive -outfile progressive.jpg original.jpg and then taking the first 350000 bytes with dd if=progressive.jpg of

问题 I cant get imread to work, its same problem as this guy: OpenCV imwrite 2.2 causes exception with message "OpenCV Error: Unspecified error (could not find a writer for the specified extension)" on Windows 7 I just dont wannt use the workaround. Anyone know the problem? Using windows 7 64bit 回答1: The problem was due to mixing up debugging and release builds. If building in debug mode, the debug libs are needed. On unix this dont seem to be a problem. 回答2: imread(filename) doesn't load any data

问题 guys! I'm looking for pure python implementation of jpeg writing (reading will be nice, but not necessary) library. I've founded only TonyJPEG library port at http://mail.python.org/pipermail/image-sig/2004-November/003055.html But the problem is this library doesn't support writing. Any ideas? UPD: I need to modify jpeg algorithm (starting from DCT) to make working prototype. UPD2: The best decision for me was to port Jpeg library from the another language. I've chosen TonyJPEG library,

问题 I am trying to convert gray scale images to RGB using the imagemagick command-line tools. It is working fine for PNG images, using: convert image.png -define png:color-type=2 result.png (taken from an answer to "How to convert gray scale png image to RGB from comand line using image magick") Although checking with identify -format %r result.png will still return DirectClass Gray , I can see it worked using gdalinfo as there are now 3 bands / channels listed: gdalinfo [successfully converted

问题 How to render JPEG/PNG file data contained in Javascript variable? Is it possible ? What javascript libraries needed ? Browser in use is FF / IE. Thanks 回答1: Modern browsers support inline images. So you could convert the binary data to a base64 encoded string and then append it to the DOM: var img = document.createElement('img'); img.src = 'data:image/gif;base64,R0lGODlhEAAOALMAAOazToeHh0tLS/7LZv/0jvb29t/f3//Ub//ge8WSLf/rhf/3kdbW1mxsbP//mf//

问题 In my iOS app, I'm downloading jpeg images from the web, and I'm wondering how to find the correct width and height of the image so I can display it properly in my iOS app. For example, How do I get the width and height of this jpg image? 回答1: you can get Image Height and Width like:- NSData *imageData = [NSData dataWithContentsOfURL:imageUrl]; UIImage *image = [UIImage imageWithData:imageData]; NSLog(@'image height: %f',image.size.height); NSLog(@'image width: %f',image.size.width); UPDATE:-

问题 I am working on an iphone app and targeting iOS 4.0 or later. I am trying to add an image to UIImageView, and image is in jpeg format . This is what I have done so far.. UIImageView *bgImageView = [[UIImageView alloc] initWithFrame:CGRectMake(0.0, 0.0, 320.0, 246.0)]; bgImageView.image = [UIImage imageNamed:@"background"]; [self.view addSubview:bgImageView]; [bgImageView release]; I have added two images, background.jpg (as normal 1x image) background@2x.jpg (for 2x / retina display). But

问题 this question might be an "Open Question" and many of you might be eager to close it, but please don't. Let me explain. As we all know, JPEG has two kinds of compression (at least in Photoshop save dialog) optimized, where image was loaded kinda like line-by-line progressive, where image was loaded first mosaic-like, the progressively better till the original resolution I have read a lot of PNG/JPEG optimization articles before, but now I encountered this awesome third kind compression, from

问题 I've seen several examples of making compressed JPG images from Java BufferedImage objects by writing to file, but is it possible to perform JPG compression without writing to file? Perhaps by writing to a ByteArrayOutputStream like this? ImageWriter jpgWriter = ImageIO.getImageWritersByFormatName("jpg").next(); ImageWriteParam jpgWriteParam = jpgWriter.getDefaultWriteParam(); jpgWriteParam.setCompressionMode(ImageWriteParam.MODE_EXPLICIT); jpgWriteParam.setCompressionQuality(0.7f);

问题 Any PHP functions that deal with JPEGs don't seem to be working on my server. This code: <?php $im = imagecreatetruecolor(120, 20); $text_color = imagecolorallocate($im, 233, 14, 91); imagestring($im, 1, 5, 5, 'A Simple Text String', $text_color); header('Content-type: image/jpeg'); imagejpeg($im); imagedestroy($im); ?> creates an empty file. Using a GIF or PNG function will create an image containing the text "A Simple Text String" as expected. This: $im = imagecreatefromjpeg("test.jpg");