jpeg

问题 I am struggling to successfully decode a JPEG image from bytes, back to JPEG again. I started from encoded frame from a MJPG bytes stream, which I want to decode in order to manipulate with OpenCV. I am a bit of a newbie at Python, numpy, opencv etc! I now have the frame JPG data in a text file as: b'\xf\xd8\xff\xdb\x00....etc etc for purposes of testing: code seems to fail when I try to Resize the numpy array to the original video stream resolution (640, 480) on line 14 (npFlat.reshape((640

问题 I want to get raw jpeg data - no metadata. I'm very confused looking at the jpeg "standards". How correct is my understanding of the marker "tree"? 0xFFD8 - Identifies the file as an image 0xFFE? - EXIF, JFIF, SPIFF, ICC, etc 0x???? - the length of the tag 0xFFD8 - Start of Image 0xFFE0 - should follow SOI as per spec, but often preceded by comments ??? 0x???? - Matrices, tags, random data ??? There are never other markers in-between these markers? Or these include the matrices and such?

问题 While saving jpg thumbnails from tiff (CMYK) file I'm encountering the following problem: Thumbnail created with color mode conversion from CMYK to RGB gets blue hue: Thumbnail created from the same tiff in photoshop (no ICC profile, not converted to sRGB, RGB only) get the colors the right way: Thumbnails created without color mode conversion (jpeg with CMYK) gets similar results to the photoshopped ones but are not usable for the web (still blue). Code snippet: img = Image.open(img_tiff)

问题 Using OpenCV, Whenever I save an image (from a camera stream) as JPG to the disk. The file size in bytes on the disk differs depending on the JPEG quality as expected. However, whenever I read the images regardless of the file size on the disk, the memory size remains constant. Is this normal? Also, there seems to be a massive difference in the disk and memory size of the image. I was expecting a much smaller memory size, somewhat relative to the disk size. For e.g. import sys import cv2 cv2

问题 Using OpenCV, Whenever I save an image (from a camera stream) as JPG to the disk. The file size in bytes on the disk differs depending on the JPEG quality as expected. However, whenever I read the images regardless of the file size on the disk, the memory size remains constant. Is this normal? Also, there seems to be a massive difference in the disk and memory size of the image. I was expecting a much smaller memory size, somewhat relative to the disk size. For e.g. import sys import cv2 cv2

问题 Get .txt file instead of .jpg - using Webclient and DownloadFile(); I'm trying to download the .jpg from this URL: http://1.bp.blogspot.com/_pK6J3MTn5co/S6kuH3aqbeI/AAAAAAAACUY/06axvmjU91k/s1600-h/avengers02_B&W_UL.jpg Using this code: private void TEST_button1_Click(object sender, EventArgs e) { WebClient MyDownloader = new WebClient(); MyDownloader.DownloadFile(@"http://1.bp.blogspot.com/_pK6J3MTn5co/S6kuH3aqbeI/AAAAAAAACUY/06axvmjU91k/s1600-h/avengers02_B&W_UL.jpg", @"c:\test.jpg"); }

问题 How can we extract images(only images) from PDF. I used many online tools, they all are not universal. In most of the PDF, it tools the screenshot of the whole image instead of the image. PDF link -> sg.inflibnet.ac.in:8080/jspui/bitstream/10603/121661/9/09_chapter 4.pdf 回答1: Here is some code that reads a PDF-File using pyPdf, extracts images and yields them as a PIL.Image . You need to modify it to your needs, it's just here to demonstrate how to walk the object tree. import io import pyPdf

问题 How can we extract images(only images) from PDF. I used many online tools, they all are not universal. In most of the PDF, it tools the screenshot of the whole image instead of the image. PDF link -> sg.inflibnet.ac.in:8080/jspui/bitstream/10603/121661/9/09_chapter 4.pdf 回答1: Here is some code that reads a PDF-File using pyPdf, extracts images and yields them as a PIL.Image . You need to modify it to your needs, it's just here to demonstrate how to walk the object tree. import io import pyPdf

问题 So I'm reading in files from a directory, figuring out which way they need to be rotated. Rotating and then saving. That part works... The issue is, after it saves the file it gets recompressed and I go from 1.5meg images to 250k images. I need to keep the file size around the original. I tried using jhead.exe and calling it from a command line but couldn't get any of my arguments to pass in correctly. Here's my code snipit to detect, rotate, and save. foreach (FileInfo f in dir.GetFiles("*

问题 I am using the excellent modification to Python's PIL by Etienne from here. What I need is exactly what the modification does - to save a JPEG file using the same quantization tables as the original. Doing it through that modification seems elegant, I'm currently achieving that by using a hodgepodge of C code. My problem is that I get a JPEG file object in PIL, but after any modification it becomes an object of some other type. What I want is to take the image, crop it and save it with the