Fix a blurry logo in an Outlook signature

A logo that looks crisp in your design file but soft in an Outlook signature is almost always a raster image problem, not a vector problem. Outlook signatures display logos as pixel-based images such as PNG or JPEG, so whatever sharpness the original vector artwork had is limited by the pixel image you export from it and by how Outlook and the recipient's mail app scale that image. The usual fix is to export a fresh PNG from the master vector file at a higher pixel size than the logo will appear, then insert it so it displays at its intended, smaller size.

Which file is actually in your signature

Three different things are often called "the logo," and the difference matters here. Vector artwork is built from paths and scales without losing sharpness, and it typically lives in a design source file or an export such as SVG, EPS, AI or PDF. An embedded raster image is a pixel image placed inside one of those files, which means a file with a vector-format extension can still contain a low-resolution picture. A raster preview or export is the PNG or JPEG generated from the artwork, and this is what ends up in an email signature.

Because email signatures rely on raster images, the vector master matters only as the source you export from. Before exporting, confirm that the master really contains editable paths: open it in a vector editor and switch to an outline or wireframe view. Clean letterforms and shapes drawn as outlines indicate vector paths; a single rectangular frame with no inner structure indicates an embedded raster image, and exporting from it will not produce a sharper result. A filename or extension alone is not proof either way.

Likely causes of a blurry signature logo

No specific symptoms, Outlook version or file details were supplied, so the causes below are possibilities to test rather than a confirmed diagnosis. Each one comes with a check that helps separate it from the others.

• The image is too small for the display. A PNG exported at exactly the size it appears will look soft on high-density screens and when Windows display scaling is above 100 percent, because the system enlarges it. Check: note the image's pixel dimensions and compare them with how large it appears in the signature.
• The image was resized inside Outlook or Word. Dragging the corner handles to enlarge a small image stretches its pixels. Check: if the logo was made bigger after insertion, that is a strong candidate.
• The image is a JPEG. JPEG compression adds soft edges and blocky artifacts around text and flat color, which logos have plenty of. Check: look at the file type and zoom in on edges for smudging or speckling.
• The source was already low resolution. A logo copied from a website, a screenshot or an old document carries its blur forward. Check: open the image file on its own at 100 percent zoom; if it is soft there, the problem predates Outlook.
• The image was compressed or converted on insertion. Office applications can downsample images, and pasting a logo from another document may bring a reduced copy. Check: insert the same file again using the picture insert option instead of copy and paste, and compare.
• The recipient's mail app rescales the image. Different clients and devices render signatures differently, so a logo can look fine to you and blurry to someone else. Check: send test messages to accounts opened on a desktop client, a webmail client and a phone.

Correcting the logo

Start from the verified vector master rather than the image currently in the signature. Decide how large the logo should appear, then export a PNG at roughly two times those pixel dimensions, which is a common practice for keeping images sharp on high-density screens. PNG keeps flat colors and text edges clean and supports transparency, though a transparent logo can disappear against a dark-mode background, so a version with a solid or subtly padded background is worth considering if your audience uses dark mode.

The larger file only helps if it is shown at the smaller size. In Outlook's signature editor, insert the image with the picture insert option, then set its displayed width and height to your target size through the picture size settings rather than by dragging. If you or an IT team manage signatures as HTML, the same idea looks like the snippet below, where the file itself is twice the size set in the width and height attributes.

<img src="logo@2x.png" width="160" height="48" alt="Company name" style="display:block; border:0;">

In that example the PNG would be exported at 320 by 96 pixels; the numbers are illustrative and should be replaced with your logo's real proportions. Setting both dimensions explicitly, in the same aspect ratio as the file, reduces the chance that a mail client stretches or squashes the image.

Keep the file size reasonable. A logo that is many times larger than needed adds weight to every message and may be handled less predictably by some clients. Simple artwork exported as PNG at about twice the display size is usually small.

SVG is a tempting shortcut because it would stay sharp at any size, but email clients have inconsistent or no support for SVG in messages and signatures, so it is not a dependable fix. Classic Outlook for Windows, which uses Word to render messages, is a common example of a client where a raster image is the safer choice.

Verifying that the fix worked

• View the signature at your normal display scaling and, if possible, on a second screen with a different pixel density.
• Send test messages to yourself in at least one desktop client, one webmail client and one phone mail app, and inspect the logo at its displayed size.
• Reply to and forward a test message, since some clients re-encode images in replies.
• Check the received image's pixel dimensions where your client allows it; if they are smaller than what you exported, something in the sending or receiving path is downsampling it.
• If the logo is sharp in a new message but blurry in replies or on one specific device, the remaining issue is that client's handling rather than your file.

What this guidance cannot confirm

Without details about your Outlook version, operating system, display settings, the image currently in the signature and where the blur appears, it is not possible to say which cause applies. The checks above are designed to narrow that down. If the logo stays blurry after a correctly sized PNG export from verified vector artwork, the next useful information is a description of exactly where it looks soft, whether in the signature editor, in sent items or only for certain recipients, since each points to a different stage of the process.

If you need to re-export or rework the logo, use the official master file supplied by the brand owner. Having a logo file available to download is not the same as having permission to alter its artwork, fonts or trademark, so changes beyond a straightforward export should go through whoever manages the brand.