Image Compressor

Image compression & format conversion tool guide

What you will get (overview)

• How compression really works: the trade-off between file size, visual quality, and dimensions.
• Format selection strategy: when to use WebP/JPEG/PNG/AVIF/ICO and why compatibility matters.
• Practical presets: recommended ranges for web images, screenshots, and favicons.
• Privacy boundary: OnesAPK processes images locally (Client-side); avoid handling sensitive images on untrusted devices.

Typical use cases (engineering-oriented)

• Web performance: reduce image size to speed up page loads and improve user experience.
• Pre-upload optimization: shrink phone photos or large screenshots before uploading to tickets/IM/docs.
• Generate favicons/icons: convert a logo into ICO and control dimensions.
• Frontend experimentation: compare output size across formats and quality settings to pick a production strategy.

Quick glossary

• [Lossy/Lossless] Lossy vs lossless compression; lossy is smaller but may lose details.
• [Quality] A 0-100-like knob controlling compression strength vs clarity.
• [Resize] Changing pixel dimensions; resizing often reduces size more than only lowering quality.
• [Aspect ratio] The width/height ratio; keeping it prevents distortion.

Best practices

• Resize first, then compress: e.g., for web display, scale 4000px-wide photos down to ~1200–1920px.
• Default to WebP for the web: a good balance of quality and size in modern browsers.
• Use PNG for transparency: logos/icons/UI often need alpha; photos typically work better as JPEG/WebP.
• Practical quality ranges: 70%–85% for common web images; increase if blurry, decrease if size is critical.
• Boundary note: this tool does not provide legal/compliance advice; redact sensitive images (IDs, faces, internal dashboards) and process them only on trusted devices.

Related tools

• OnesAPK Toolbox (Home) Explore more privacy-friendly, client-side tools
• OnesAPK Code to Image Generate shareable images from code snippets

This page explains how to use a small in‑browser tool for image compression and format conversion. You do not need to install anything: you can quickly make images smaller, change their size, and convert formats directly in the browser.

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1. What can this tool do?

• Compress image file size: significantly reduce file size while keeping acceptable visual quality, so it is easier to upload and share.
• Resize images: change large images to a suitable width/height, for example from 4000×3000 to 1200×900.
• Keep or break aspect ratio: decide whether the image should be scaled proportionally, to avoid or allow stretching.
• Convert formats: convert between JPG, PNG, WebP, AVIF, ICO and other supported formats.
• Preview and download the result: compare before/after size and appearance, then download if you are satisfied.
• Local processing & privacy: OnesAPK Image Compressor runs entirely in your browser. Images are not uploaded to a server, which makes it safer for pictures containing personal or sensitive information.

Supported input formats: JPEG / JPG, PNG, WebP.

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2. Basic usage

1. Upload an image
   • Click the blue upload button in the left panel and choose a local file; or
   • Drag and drop an image file into the dashed area.
2. Adjust options (optional)
   • Change width / height if needed;
   • Choose an output format;
   • Move the quality slider to control compression strength.
3. Start conversion
   • Click the Convert button and wait for processing.
4. Check the result and download
   • The bottom‑right panel shows the compressed image, file size and compression ratio;
   • Click Download result to save the new image.

If you only want to “make the image a bit smaller and send it out”, leaving everything at default and clicking Convert is usually enough.

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3. Layout overview

3.1 Left side: upload & options

• Upload area:
  • Supports both click‑to‑select and drag‑and‑drop;
  • After upload, shows file name, original size and resolution (for example 2.3 MB, 4000x3000).
• Size settings: width / height input boxes to set the target resolution.
• Keep aspect ratio checkbox: controls whether scaling is proportional.
• Format dropdown: choose the output format (WebP, JPEG, PNG, AVIF, ICO, original, etc.).
• Quality slider: use a percentage to control how strong the compression is.
• Buttons:
  • Convert: run compression / conversion;
  • Reset: clear the current image and parameters and return to the initial state.

3.2 Top right: original image info

• Shows a preview of the original image and its current file size;
• If no image is uploaded yet, this area reminds you to upload one first.

3.3 Bottom right: result info

• Shows a preview of the compressed / converted image;
• Displays:
  • Output file size;
  • When available, a “compression ratio xx%” to compare size before and after;
• The Download result button saves the processed image.

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4. How to use each option

4.1 Width / Height

• Width: target image width in pixels.
• Height: target image height in pixels.

Common patterns:

• Change only the width, for example from 4000 to 1200;
• Change only the height, for example from 3000 to 800;
• Change both width and height for a specific size.

4.2 Keep aspect ratio

• Checked (recommended):
  • If you change only width, height is calculated automatically based on the original ratio;
  • If you change only height, width is calculated automatically;
  • The image will not be stretched or squashed.
• Unchecked:
  • Width and height are independent;
  • You can force any size, such as 500×500;
  • The image may become distorted.

If you are unsure what to do, it is safer to keep this checked and modify only one value.

4.3 Output format (Format)

Typical choices and scenarios:

• WebP: default recommendation; high compression, good for web and articles.
• JPEG: best compatibility; suitable for general photos and screenshots.
• PNG: supports transparency; good for logos, icons and UI elements.
• AVIF (shown only if the browser supports it): can be even smaller than WebP; good when you control the target environment.
• ICO: icon format, typically used to generate favicon.ico for websites.
• Original format: keeps the same format as the uploaded image and only changes size and compression.

4.4 Quality

• Typically ranges from 10% to 100%;
• Closer to 100% → better quality but larger file size;
• Closer to 10% → much smaller files but more visible artifacts.

Practical ranges:

• General web or document images: 70%–85%;
• When file size is more important than quality: 50%–70%;
• For detail‑sensitive content (e.g. design work, portfolios): 90%–100%.

For PNG output, the image is already near‑lossless, so the quality setting has less impact.

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5. Example use cases

5.1 Compressing an image for articles or web pages

1. Upload a large original image.
2. Keep Keep aspect ratio checked and change only the width, for example to 1200.
3. Choose WebP or JPEG as the output format.
4. Set quality to around 75%–85%.
5. Click Convert, check that both quality and file size are acceptable, then click Download result.

5.2 Generating a website favicon.ico

1. Prepare a square logo image (for example 512×512 PNG/JPEG).
2. Upload the image.
3. Keep Keep aspect ratio checked and set width and height to 256 or 128.
4. Choose ICO as the output format.
5. Click Convert, then Download result to get the favicon.ico file.

You can then place this favicon.ico file in your website according to your framework or server configuration.

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6. Troubleshooting

6.1 “Unsupported format” when uploading

Possible reasons:

• The file is GIF, HEIC, TIFF, RAW or another unsupported format;
• The file is corrupted or not actually an image.

Try opening it with your system viewer or another tool first; if needed, convert it to JPG/PNG before using this tool.

6.2 Result looks too blurry

• Check whether the quality is set too low; try raising it to around 80%;
• Check whether the image was scaled down too aggressively, e.g. from width 4000 straight down to 400;
• Check whether the original image itself is already blurry.

Increasing the quality and/or using a larger target size usually improves the result.

6.3 No AVIF option

• The tool detects whether the browser supports exporting AVIF;
• If not supported, the AVIF option will not be shown.

You can try:

• Updating your browser;
• Using another modern browser;
• Or simply using WebP as a high‑compression alternative.

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7. Summary

If you just want to get started quickly, you can follow this short checklist:

1. Upload or drag and drop an image.
2. Keep Keep aspect ratio checked and change only one dimension (for example, width).
3. Choose WebP or JPEG as the output format and set quality to 70%–85%.
4. Click Convert and check the preview.
5. Click Download result to use the compressed image.

Once you are familiar with these steps, you can fine‑tune size, format and quality for different use cases.