On my MacBook Pro with retina display, when I take a screenshot, the image is saved with a DPI of 144. But, using ImageOptim to compress the image with Strip JPEG/PNG Metadata enabled will remove (or reset) the DPI setting to 72 DPI - resulting in a double sized image when displayed in Preview and Quick Look. Here is how I correct this.
I really don’t know how to explain today’s post. In short: I want to copy drawings and images out of Microsoft Office in PNG format. On macOS, copy-and-paste seems to prefer the TIFF format, resulting in large Office files. I’d rather the images be converted to PNG, preserving transparency but providing high compression. However, this is more complicated than it seems, because of limitations in Office and PowerPoint in particular...
I recently tried Crunch, an open-source tool for PNG image file optimization, currently on version 2.0.2 at the time of writing.
Lots of web pages now rely on SVG instead of PNG or JPG images. SVG stands for Scalable Vector Graphics, an XML-based vector image format that scales well, unlike bitmap images (bitmaps become pixelated when up-sized). I recently wanted a quick way to convert a SVG to PNG, and discovered modern browsers (read: Chrome and Firefox) can do this with a simple bit of code.
Microsoft PowerPoint 2016 for Mac (aka version 15) has a strange quirk - when I copy and paste images from Preview or most other applications, the image gets copied in Tagged Image File Format (TIFF). The image is practically uncompressed (or possibly minimally compressed), resulting in very, very huge PPTX files! Plus: Removing unwanted font references.