Convert PNG, JPG and WebP Without Losing Transparency or Detail

A PNG that is 8 MB, a JPG that has been saved five times, a WebP that a client’s old software cannot open. Format conversion looks like a one-click fix, but every format has a job. Converting the wrong way can remove transparency, flatten an animation, or add another generation of compression artefacts.

The useful rule is simple: start from the original, convert once, and choose the format for the destination. If you only have a compressed copy, converting it again will not restore the detail that was already lost.

What each format is for

JPG is for photographs. It compresses well, is accepted almost everywhere, and produces small files. It does not support transparency, and it is lossy. Every save can lose a little detail.

PNG is for screenshots, logos, line art, diagrams and images with transparency. It is lossless, so the edges stay sharp, but photographs become large. A PNG photo can be several times the size of a good JPG.

WebP is a modern format for the web. It can be smaller than JPG at similar quality, supports transparency, and can handle animation. Support is good in current browsers, but some email clients and older applications still do not accept it.

Converting to JPG

Use JPG when the destination expects a normal photo and does not need transparency. A product photo, a portrait, a landscape or a scanned page can all be JPG.

OpenToola fills the background with white before exporting JPG. If the image has transparent areas, they will no longer be transparent. That is fine for a photo with no transparency, and wrong for a logo that is supposed to sit on a coloured header.

JPG quality 85–90 % is a good default. Below 70 %, text and sharp edges start to show artefacts. For print, use 95 % and check the result at 100 %.

Converting to PNG

Use PNG when the image has transparency, sharp text, flat colours or fine lines. A logo, an icon, a screenshot or a chart is a better PNG than JPG.

PNG is lossless, but it is not magic. Converting a blurry JPG to PNG does not make it sharp; it only preserves the blur without adding more. Converting a large photo to PNG usually makes the file much larger without a visible benefit.

If the source is a PNG with transparency and the destination accepts PNG, keep it. Converting to JPG and back to PNG will not restore the transparency.

Converting to WebP

Use WebP for a website when you control the platform and want a smaller file. It is especially useful for large hero images and image galleries.

WebP quality 80–90 % is a reasonable starting point. Check the result in the browsers your audience uses. If the site also serves older devices, provide a JPG fallback or use a picture element with multiple sources.

Do not use WebP for an email attachment unless you know the recipient’s client supports it. JPG is still the safest choice for email.

Transparency and background colour

Transparency is the most common casualty of conversion. A logo with a transparent background saved as JPG gets a white box. If the destination has a coloured background, the box is visible and looks unprofessional.

If you must use JPG, flatten the image onto the correct background colour first. A logo for a dark header should be flattened onto the dark colour, not white. In OpenToola, JPG export uses white; prepare the image in an editor if you need another colour.

PNG and WebP preserve transparency. Check the result on the actual background, not only in an image viewer with a checkerboard.

Animation and multiple frames

A GIF or an animated WebP can contain several frames. A simple canvas-based converter exports one frame, usually the first. If the animation matters, use a tool that preserves it, or keep the original format.

Animated content is often better as a video for social media. Converting an animated GIF to JPG loses the motion entirely.

Metadata and colour

Canvas-based conversion usually strips EXIF metadata, including camera model, capture date and GPS coordinates. That is often desirable for a public website, but it can also remove the orientation tag. A photo that relied on EXIF rotation may appear sideways after conversion.

Check the result. If it is sideways, rotate it in an editor and export again. If you need the capture date for an archive, record it separately.

Browsers generally work in sRGB. A photo with a wide-gamut profile may shift slightly when converted. For web use, sRGB is the safe choice. For print, keep the original and let the print workflow handle the colour profile.

Repeated conversions

Every JPG-to-JPG save is another lossy generation. Converting JPG to PNG and back to JPG does not undo the first loss; it adds another.

Convert once from the best original you have. If you need several formats, export each one from the original, not from each other. Keep the original in a separate folder.

File size expectations

A JPG photo is usually the smallest of the three for photographic content. A PNG of the same photo is often several times larger. WebP is often smaller than JPG at similar quality, but not always; a very detailed image can produce a larger WebP than a well-tuned JPG.

A PNG logo can be smaller than a JPG logo because flat colours compress well. A photograph with transparency is unusual; if you have one, WebP is often the best compromise.

When conversion is the wrong fix

If the image is too large, resize or compress it instead of changing the format. If it is blurry, conversion will not fix it. If it is the wrong dimensions, use Resize Image.

If an application refuses a format, convert to the format it accepts, but keep the original. Do not delete the only high-quality copy after conversion.

Checking the result

Open the converted image at 100 % and compare it with the original. Check transparency on the intended background, check text edges, and check the file size. If the image is for a website, test it in a browser; if it is for print, check a proof.

Keep the original until the converted file has been accepted by the destination.

Choosing a format by use case

A product photo for a marketplace: JPG, 85–90 % quality, resized to the listing’s dimensions. A transparent logo for a website: PNG or WebP. A screenshot of a chat: PNG. A hero image for a modern site: WebP with a JPG fallback.

A scanned document with text: keep PDF for the document; if you need an image, PNG or a high-quality JPG. A photo for email: JPG. A photo for print: keep the original, or export a high-quality JPG/TIFF from the source.

The destination decides more than the format’s reputation. The “best” format is the one the recipient can open without losing what matters.

Screenshots and logos

Screenshots contain text and sharp UI edges. JPG compression makes the text fuzzy, especially at low quality. PNG keeps it crisp. If the screenshot is very large, WebP at high quality can reduce the size without the worst JPG artefacts.

Logos need transparency and sharp edges. PNG is the safe choice. WebP is a good web alternative. JPG is the wrong choice unless the background is already part of the design.

Print and web

For print, avoid unnecessary format conversion. A print shop may ask for a PDF, TIFF or high-quality JPG. Converting a good original to a small WebP for the web and then trying to print it will not work; the detail is gone.

For web, export a separate copy at the display size. Keep the print original untouched. A single image rarely serves both well.

Common mistakes

• Converting a transparent logo to JPG.
• Converting a screenshot to low-quality JPG.
• Saving the same JPG repeatedly.
• Converting a small image to a huge PNG and expecting more detail.
• Deleting the original after conversion.
• Using WebP in an email that cannot display it.
• Assuming a format change fixes blur or wrong dimensions.

Testing compatibility

Open the converted file in the application the recipient will use. A WebP may look fine in your browser but fail in an old email client. A PNG may be perfect on a website but rejected by a portal that accepts only JPG.

If the file is for a public website, test the page in more than one browser. If it is for a client, ask which format they prefer before converting a whole folder.

Privacy

OpenToola converts the image in the browser. The file is not uploaded and is not stored in an account. The converted copy is downloaded to your device.

That is useful for client work and personal photos. Delete the downloaded file after uploading if it contains sensitive information, and keep the original in a private folder.

Tools mentioned

• Convert Image
• Compress Image
• Resize Image
• OpenToola Guides