The image that will not open, in a format that will
A picture saved from the web turns out to be AVIF or WebP, a photo from an iPhone is HEIC, a download is an SVG or a BMP, and the program or form in front of you will not take it. MamePress converts it to JPEG, PNG or WebP, which open almost anywhere, or to an ICO for a favicon. The whole job runs inside your browser: nothing is uploaded to a server, there is no account to create, nothing to pay, and no watermark on the result.
The conversions people need
| From → to | What to know |
|---|
| AVIF → JPG | For the program or site that does not open AVIF yet |
| WebP → PNG or JPG | PNG keeps transparency; JPEG fills it with a colour |
| HEIC → JPG | iPhone photos, on Windows too, up to 30 at a time |
| SVG → PNG | Drawn at the size the SVG states (see below) |
| PNG → ICO | A favicon with several sizes in one file |
| BMP or GIF → PNG or JPG | A GIF is converted as its first frame |
What it reads and what it writes
It reads JPEG, PNG, WebP, AVIF, HEIC, HEIF, SVG, BMP and GIF, up to 50MB a file, and writes PNG, JPEG, WebP or ICO. It does not write AVIF or GIF, because a browser has no encoder for either, and it does not open TIFF, because browsers do not read it. An animated GIF or WebP becomes its first frame. The list holds up to 30 images at a time; clear it to convert the next batch.
Favicons: several sizes in one .ico
An ICO file can hold more than one size of the same icon, and each place that shows it picks the one that fits: 16px in a browser tab, 32px in a bookmark list, larger on a desktop shortcut. 16, 32 and 48px are included to begin with, and 64, 128 and 256px can be ticked as well. Start from an image at least as large as the largest size you tick, since a small picture stretched to 256px comes out soft.
SVG to PNG: the size is the SVG's
An SVG has no pixels until something draws it. Here it is drawn at the width and height written in the file; one that gives none falls back to a small browser default (300×150, or 150px tall when it has a viewBox). There is no setting to draw it larger, so for a big, sharp PNG put the size you want into the SVG first. Enlarging the PNG afterwards will not add the detail back.
Change your mind without starting again
The images convert as soon as they arrive. To try another format or quality, change the setting and press Convert again with these settings: every image in the list is made again from its original file, so nothing is compressed twice. A JPEG saved as a JPEG keeps the print resolution (DPI) recorded in the original.
What it does not do
- · Write AVIF or GIF, or read TIFF. Browsers cannot, so neither can a tool that runs in one
- · Keep an animation. Animated GIF and WebP become their first frame
- · Enlarge an SVG. It is drawn at the size it states
- · Convert to PDF, text or SVG. The results are pictures: PNG, JPEG, WebP or ICO
How to use it (three steps)
- 1. Under Convert to, choose PNG, JPEG, WebP or ICO
- 2. Drag and drop your images (or click to choose them)
- 3. Download each one, or press Download all as ZIP
Frequently asked questions
Are my images uploaded anywhere?
No. Every conversion runs inside your browser, on your own device. Neither the original nor the converted file is sent to a server; there is no upload endpoint to send them to, so there is also nothing to delete afterwards.
How do I convert AVIF to JPG?
Choose JPEG under "Convert to" and drop the AVIF files in. Each one is converted as soon as it arrives, and you can download them one by one or press "Download all as ZIP". AVIF is opened by your browser's own decoder, so there is nothing to install. The same goes for WebP to JPG or PNG.
Can I convert HEIC photos from an iPhone to JPG?
Yes. HEIC and HEIF are decoded inside the page, not by the browser, so this works in Chrome, Edge and Firefox on Windows as well as on a Mac. Choose JPEG and drop in up to 30 photos at a time, then save them one by one or as one ZIP.
How do I make a favicon (.ico) from a PNG?
Choose ICO. One .ico file holds several sizes: 16, 32 and 48px are ticked to begin with, and 64, 128 and 256px can be added. The browser tab uses the small one and a desktop shortcut a larger one, so the icon stays sharp in each place. An image that is not square is centred, with transparent space on the shorter sides. At least one size has to stay ticked.
What size is a PNG made from an SVG?
An SVG is drawn at the size it states. If its width and height are given in pixels, that is the size of the PNG. If they are not, the browser falls back to a small default: 300×150 with no viewBox, or 150px tall with one. However fine the drawing is, the PNG is that size, and enlarging it afterwards will not bring the detail back. To get a large, high-quality PNG, write the width and height you want into the SVG first, then convert it.
Can I change the format or quality after the images are in?
Yes. Once images are loaded, a "Convert again with these settings" button appears at the end of the settings row. Change the format, the quality, the fill colour or the ICO sizes, press it, and every loaded image is converted again from its original file, so nothing degrades however many times you do it. Changing a setting alone does not change the results: until you press the button, the downloads are the files made with the previous settings.
What does the quality setting do, and what happens to transparency?
JPEG and WebP have a "Quality" slider from 40 to 100, set to 90 to begin with; lower means a smaller file. PNG keeps every pixel and has no quality setting. JPEG cannot hold transparency, so transparent areas are filled with a colour you choose, white to begin with. PNG and WebP keep transparency as it is.
Does it keep the DPI of a scanned JPEG?
When a JPEG is saved as a JPEG, yes. Nothing is scaled, so a 300dpi scan is still recorded as 300dpi and drops into Word or InDesign at its original size, wherever the original recorded it (the JFIF header or EXIF). Other conversions do not carry DPI over, and a JPEG made from a PNG or another format has none to carry.
Which formats can it read and write? Can it make AVIF, GIF or TIFF?
It reads JPEG, PNG, WebP, AVIF, HEIC, HEIF, SVG, BMP and GIF, up to 50MB a file, and writes PNG, JPEG, WebP or ICO. It does not write AVIF or GIF: a browser has no encoder for them, and offering them would mean renaming a file without converting it. An animated GIF or WebP is converted as its first frame, so the result does not move. TIFF cannot be opened at all, because browsers do not read it.
