Retina Display Email Signature

A retina display email signature uses images sized at higher pixel density than their displayed dimensions, so they render sharply on high-DPI displays (Apple Retina, modern Android phones, 4K monitors). The convention is to provide the image at 2x the display size and constrain the displayed size via HTML `width` and `height` attributes or CSS. For example, a logo displayed at 200 pixels wide is sourced as a 400-pixel-wide image and shown at 200px. On standard displays the browser scales the 2x source down with no visible quality change; on retina displays the source resolution matches the screen resolution, producing a sharp image. SVG logos solve the retina problem entirely because they scale vectorially without resolution loss, but SVG support varies in older email clients. PNG is the common fallback with 2x raster source. File size doubles compared to a 1x source, which is the main trade-off; compression with tools like TinyPNG or ImageOptim mitigates this. Retina-ready signatures look noticeably more polished than 1x signatures, particularly on iPhones and MacBooks where most professional email is read.