If you are using a convert command line you can execute it with these parameters: convert source.pdf[0] output.jpeg Note that the page count of ImageMagick is 0-based. So [0] means ‘page 1’. To select, say the 4th page, you’d have to use [3]. This syntax does not only work for PDF input. It also works … Read more
JPEG: YES — use progressive scan. It makes files smaller (each pass gets its own Huffman table), and partial rendering looks quite good. GIF: NO — it’s unlikely to make the file smaller, partial rendering is poor, and it’s pointless for animGIFs. It’s best not to use GIF at all (yes, even for anims). PNG: … Read more
People say that ImageMagick is much faster. At best just compare both libraries and measure that. Prepare 1000 typical images. Write two scripts — one for GD, one for ImageMagick. Run both of them a few times. Compare results (total execution time, CPU and I/O usage, result image quality). Something which the best everyone else, … Read more
You can view compress level using the identify tool in ImageMagick. Download and installation instructions can be found at the official website. After you install it, run the following command from the command line: identify -format ‘%Q’ yourimage.jpg This will return a value from 0 (low quality, small filesize) to 100 (high quality, large filesize). … Read more
As correctly answered above, using a “typical” JPEG encoder at quality 100 does not give you lossless compression. Lossless JPEG encoding exists, but it’s different in nature and seldom used. I’m just posting to say why quality 100 does not mean lossless. In JPEG compression information is mostly lost during the DCT coefficient quantization step … Read more
PNG’s are pixel perfect (non-lossy), and require very little extra CPU energy to display. However, large PNGs may take longer to read from storage than more compressed image formats, and thus be slower to display. JPG’s are smaller to store, but lossy (amount depends on compression level), and to display them requires a much more … Read more
The file is actually a PNG with the wrong file extension. “0x89 0x50” is how a PNG file starts.
I wrote a GUI for all image optimization tools I could find, including MozJPEG and jpegoptim that optimize Huffman tables, progressive scans, and (optionally) remove invisible metadata. If you don’t have a Mac, I also have a basic web interface that works on any platform.
That’s funny you asked this, I just did this recently for my work’s site and I was thinking I should write a tutorial… Here is how to do it with PHP/Imagick, which uses ImageMagick: $usmap = ‘/path/to/blank/us-map.svg’; $im = new Imagick(); $svg = file_get_contents($usmap); /*loop to color each state as needed, something like*/ $idColorArray = … Read more
Here’s a version that’s much simpler – not sure how performant it is. Heavily based on some django snippet I found while building RGBA -> JPG + BG support for sorl thumbnails. from PIL import Image png = Image.open(object.logo.path) png.load() # required for png.split() background = Image.new(“RGB”, png.size, (255, 255, 255)) background.paste(png, mask=png.split()[3]) # 3 … Read more