When is ICO better than ICNS?
ICO images are flexible, extensively supported, and recognized by different software programs and web browsers, while ICNS images are incompatible with non-MacOS programs or software and enjoy limited online usage because most web browsers do not support them. This makes ICO format ideal for creating professionally sharp icons for desktop PC shortcuts like applications, files, and folders.
When is ICNS better than ICO?
ICNS images are smaller, highly web-responsive, and enhance online user experience, while ICO images are larger, less web-responsive, and abridge online user experience. This makes ICNS a better format than ICO when there is limited storage space.
ICNS versus ICO Table Comparison
| Aspect/Factor | ICO | ICNS |
| Transparency | Supports transparency | Supports alpha channel transparency |
| File Size | Larger than ICNS files. | Smaller files than ICO files. |
| Image Quality | High-quality images. | High-quality images. |
| Performance | Increased image loading times than ICNS. | Decreased image loading times than ICO. |
| Structure | Vector-based: With Icon directory, image mask, XOR bitmap, block, and the AND bitmap. | Raster-based: The file extension starts with the file headers and ends with the binary icon data. |
| Animation | Supports animations. | Supports animations. |
| Storage | Requires more storage space than ICNS. | Requires less storage space. |
| Compression | Uses PNGOUT/TinyPNG lossless compression. | Supports PackBits and lossless compression. |
| Browser Support | Wider web browser support than ICNS. | Limited browser support compared to ICO. |
Differences and similarities between ICO and ICNS images
The ICO versus ICNS comparison table above shows that the formats differ in storage needs, web browser support, file size, structure, and web performance. However, they are similar in supporting lossless compression, alpha channel transparency, high-quality images, and animations.
Transparency
The ICNS and ICO file extensions support alpha channel transparency. The contents or features of the ICNS file typically include one or more images in PNG format. The format acts as a base for the ICNS because it allows transparent backgrounds to be integrated into images. The ICNS file supports 1-bit and 8-bit alpha channels.
ICO files support icons with varying color depths and dimensions and 8 transparency bits. This feature allows graphic designers and web developers to add semi-transparent areas, including glass-like effects, anti-aliasing, and shadows, to an image.
File Size
ICO and ICNS files store multiple image resolutions and metadata within a single file, allowing for scalable icons. The size of these files can vary significantly. ICNS files typically range from 4 KB to 660 KB, depending on the images they contain, while ICO files have no specific size limit, as their size depends on the number and resolution of images included.
ICNS files may use PackBits compression, a less efficient method compared to modern standards. On the other hand, .ICO file format often use PNG compression, which employs more advanced algorithms like Huffman coding and LZ77 for lossless compression. As a result, ICO files generally achieve more efficient compression while retaining image details. Therefore, ICO files are often more efficient in terms of file size compared to ICNS files using older compression methods.
Image Quality
ICO and ICNS images are high-quality. The ICNS file supports 1-bit and 8-bit alpha channels, whereas ICO supports a maximum of 24 bits per color channel and 8 bits of transparency. ICNS files also support more color profiles, including IHDR, ARGB, and RGB color profiles.
Since both file types preserve all image details during lossless and PackBits compression, neither ICNS nor ICO format loses image quality. However, ICO supports fewer color profiles than ICNS. Hence, choose ICNS images instead of ICO images for excellent image quality.
Performance
ICNS files are smaller than ICO files. While both formats store multiple files, the compression techniques and file size differ. ICNS supports PackBits, which encode redundant data and result in 26kb to 660kb file sizes, while ICO's TinyPNG/PNGOUT algorithms generate files without size limits.
Multiple ICO files are larger, consume more bytes, load slower on websites than ICNS files, and are easily transferred over low network bandwidths. Therefore, choose ICNS instead of ICO for a better online user experience, optimized search engines, and high web responsiveness.
Structure
ICNS is a raster-based format, while ICO is a vector-based format. The structural differences make both formats different and difficult to compare. An ICNS file has a file header and binary icon data. Its file extension header comprises 8 bytes of data, four for the magic literal and four for the file length.
The ICNS icon specifies the file size and type stored in the icon data section, followed by the binary image data. The file size describes the size of the binary section. In contrast, an ICO file starts with an Icon directory (ICONDIR), which has the ICONDIRENTRY structure for every image in the ICO file.
The ICO has a contiguous block with image bitmap data closely following each image file. The file format has the AND bitmap, the XOR bitmap, and an image mask. The ICO’s image bitmap data is either in PNG or Windows BMP format, which excludes the BITMAPFILEHEADER structure.
Animation
ICO and ICNS file extensions inherently support animations, live images, and animated content. ICNS has icon features that allow computer applications and web icons to be customized and support multiple resolution levels and color depths. Both formats are ideal for creating animations or lively content.
ICNS supports 1- and 8-bit alpha channels, ideal for visually impressive and presentable animations. In contrast, the ICO file extensions support animation using icon features that enable enhanced customization of websites or computer applications that support multiple color depths and resolutions.
Storage
ICNS files are significantly smaller than ICO files because the format’s single files are smaller than the ICO files, which have limitless sizes. ICNS files need less storage space than ICO files. Both formats store files using Base64 Encoding, Content Delivery Networks, Cloud, and the package's Contents and ​Resources directory.
ICNS and ICO compressed files can last indefinitely with proper handling, good storage conditions, and the best storage medium. However, due to size differences, users should opt for the ICNS format instead of the ICO file format because of their efficient storage requirements.
Compression
ICO files support TinyPNG and PNGOUT lossless compression methods, while the ICNS extension supports lossless and PackBits compression methods. The ICNS’s PACKBITS algorithms use run-length encoding (RLE), where the redundant file information existing as repeated data is represented concisely.
The PACKBITS algorithm encodes the redundant ICNS data by storing a series of identical pixel colors. Conversely, the ICO compression process uses delta encoding for each image line of pixels. The current pixels are programmed according to the pixels within the containers.
The ICO compression algorithms ensure that the resulting files are of higher quality, as all image details are preserved, although they are comparatively larger than ICNS files. However, neither of the file formats uses efficient compression techniques.
Browser Support
ICNS and ICO are older file formats with compatibility issues in web browsers, platforms, software, and devices. ICO files are compatible and supported by Chrome, Firefox, Opera, and Microsoft Edge, whereas Mozilla Firefox and Google Chrome only support ICNS images or file types.
ICO files and images are unsupported by Internet Explorer and Apple Safari, while ICNS files are incompatible with Brave, Vivaldi, Opera, IE, Discord, and Samsung Internet. For high web browser compatibility, it is recommended that users convert ICNS files to PNG format.
Convert ICO to ICNS or ICNS to ICO
Use Convertjack to convert ICO to ICNS files. ICNS files are detailed, editable, easily scalable, and can be displayed optimally on varying screen sizes without losing high-resolution levels and image quality.
Convertjack is the top ICNS to ICO converter. ICO files are flexible and support multiple images with different color depths and sizes, which allows users to store icons in one file, making it easier to design icons for display on various screen resolutions.