Convert BLK to CG4

BLK to CG4 made simple. Add files or folders, pick your settings, click Convert. reaConverter handles the rest — even thousands of files.

Tired of converting BLK files one at a time? reaConverter processes entire folders to CG4 automatically. Handles large batches reliably without crashes or timeouts.

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How to Convert Multiple BLK Files to CG4?

1. Download and Install reaConverter

reaConverter is a standalone Windows app — download, install, and start converting BLK files in under two minutes.

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Install reaConverter

2. Load your BLK files

Launch reaConverter and drop in your BLK files. The software queues everything for batch processing with consistent settings.

Add files by dragging them in, browsing folders, or using the right-click menu from Windows Explorer.

Load your BLK files into reaConverter

3. Select CG4 as output format

Pick CG4 as output format and choose the destination folder where you want to save new .cg4 files.

Select CG4 as output format

4. Start BLK to CG4 conversion

Then simply press the Convert button and your conversion will begin in no time!

Start Conversion

Once the conversion is complete, you can find your CG4 files in the destination folder you selected.

BLK to CG4 Converter

reaConverter offers the fastest, simplest solution for converting your BLK files into CG4 in seconds - all files processed on your PC for maximum privacy and speed.

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Do more with your files

Converting BLK files for use in a workflow? reaConverter offers many ways to process files, so you can customize them according to your requirements.

Our range of editing options includes auto-processing options such as auto-rotate, auto-crop, watermarking and more. Change Color Space, copy Metadata, set DPI, manage ICC Profile, control Bit Depth.

Conversion features
Image editing

User Reviews

Average User Rating:
Last updated on January 16, 2026
"reaConverter saved our team hundreds of hours by digitizing decades of CG4 archives in weeks—not months. Its resolution scaling preserved every detail, even in files older than some team members!"
Anna K.
Anna K.
Satisfied Customer
"Finally an app that actually opens my weird files! Saves me from format frustration daily."
Kyle Brooks
Kyle Brooks
Happy User
"This converter delivers exceptionally quick format conversions with reliable results every time."
Brian White
Brian White
Happy User
"Security was our top concern when evaluating file conversion tools. reaConverter’s offline mode and role-based access controls let us lock it down for sensitive environments. No unexpected network calls or bloat — just clean, fast conversions. Even passed our pen-testing scans without a hitch."
Marcus White
Marcus White
Healthcare IT
"An ultra-fast solution for minimizing file sizes. The entire conversion process takes just 3 minutes!"
Logan B.
Logan B.
Satisfied Customer
"I use the online converter — it’s quick and hassle-free!"
Jian Wong
Jian Wong
Happy Online User

BLK to CG4 Conversion: FAQ

What are BLK files?

The BLK file format is associated with Amiga, a type of personal computers sold under the Commodore brand during the 1980s and 1990s. BLK files store bitmap images and are part of the Amiga IFF (Interchange File Format) pack. They became obsolete together with the demise of Amiga computers and are currently compatible with a limited number of image viewers.

What are CG4 files?

CG4 is a raster format associated with CALS (Continuous Acquisition and Life-Cycle Support) — a program initiated by the US Department of Defense to capture and link military data. CG4 is compatible with a very limited number of digital graphics programs. Files with this extension contain a bitmap that often uses the CCITT4 compression, which is an old fax machine standard used for black-and-white images.

Can reaConverter convert BLK to CG4?

Yes! reaConverter instantly converts .blk to .cg4 with perfect quality preservation. With its batch processing feature, you can convert multiple files at once in just a few clicks. You can even convert images directly from Windows Explorer using the right-click menu — fast and convenient.

Can I convert BLK to CG4 online?

If you only need to convert a few BLK files to CG4 format, feel free to try our free online free online BLK to CG4 converter — perfect for small batches with no installation needed!

How can I turn BLK files into CG4 on my computer?

The best way to change BLKs to CG4s on your PC is to install a quality piece of software, such as reaConverter. This software is extremely efficient in managing a wide range of batch files conversions, including conversion from BLK to CG4.

How can I automate BLK to CG4 files conversion?

reaConverter supports all the most useful automation features such as right-click сonversion and Watch Folders for the most efficient automated files conversion in any software of this type.

Is there a way to convert BLK files to CG4 using the command prompt?

reaConverter provides full access to all its features via Windows command line, including a high-performance command-line blk to cg4 converter for batch processing.

What else can I do with reaConverter?

Convert vector imagesConvert picture color spaceConvert DICOM imagesResize photoConvert RAW photo formats

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