Somebody sends you a logo and it arrives as logo.eps. Windows shows a blank page
icon and offers to look in the Store; a Mac shows a preview that is somehow blurry.
Nothing is wrong with the file. Drop it on the
image viewer — ICO, EPS, TGA, WebP, CDR, CMX, SVG, DNG
and the rest, up to 25 MB, deleted when you close it. Then, if you want to know why
your computer had no idea what to do with it, this is the short version.
Why your operating system gives up
Showing a picture requires a decoder for that particular format, and an operating system ships the handful everybody has: JPEG, PNG, GIF, BMP. Everything else arrives in the world attached to a specific application, and the decoder came in the same box. No CorelDRAW, no CDR decoder. It is not a permissions problem or a corrupt download — your machine is being asked to read a language nobody installed.
What each of these actually is
ICO is not one image. It is a container holding the same icon at several sizes — 16, 32, 48, 256 pixels — so that a desktop can pick the one it needs instead of scaling. Open one and you are looking at a set, which is why an ICO occasionally seems to change size depending on where you saw it.
EPS is a small PostScript program that draws a picture when something runs it, usually a printer. Layout applications cannot afford to run it just to show you a thumbnail, so an EPS often carries a low-resolution preview bitmap alongside the code. That preview is the blurry thing you have seen on screen next to a logo that printed perfectly. Two different pictures, one file.
TGA — Truevision Targa — comes out of video and game work. It is simple, usually uncompressed and carries an alpha channel, which is why it survives in texture pipelines long after the format stopped being fashionable anywhere else.
WebP is Google's format for the web. It can be lossy like a JPEG or lossless like a PNG, it supports transparency, and it can be animated — so a WebP that behaves like a GIF is not a mislabelled GIF, it is a WebP doing what it does.
CDR is CorelDRAW's own document, and it is version-locked in a way that catches people: a CDR written by a newer CorelDRAW cannot be opened by an older one. "The file won't open" often means "the file is newer than the program".
CMX is Corel's exchange format, made for moving artwork between Corel applications and out to other software. If someone sends you a CMX, they were trying to be helpful.
What a viewer can and cannot give you
You get the picture, rendered. You do not get the editable thing underneath: the layers in a CDR, the paths in an EPS, the alpha channel in a TGA as something you can manipulate. Rendering flattens.
That distinction decides whether a viewer is enough. Approving a logo, checking that the right version arrived, reading a file before you forward it — a render is the entire job. Changing the artwork needs the application that made it, and no viewer substitutes for that.
When it does not open
Over 25 MB — likely a CDR with a lot of placed images, or a large uncompressed TGA. A CDR from a CorelDRAW version the renderer has not met may come through partly, or not at all; there is no fix from your side except asking for it as PDF or PNG, which is worth doing anyway when the file is only going to be looked at.
An EPS with no embedded preview still opens: it is drawn from the PostScript rather than read off a thumbnail, so what you see is the real artwork and not the blurry stand-in.
If files like these keep arriving from designers who assume you own the software they own, the image viewer is the page worth a bookmark.