HotConvertDrop your files here
or click to select
Why convert HRZ to OTB?
Fast
Your file is converted in under 30 seconds in our cloud.
Secure
Files are automatically deleted after 1 hour.
Quality preserved
Maximum quality preserved during conversion.
About the HRZ format
HRZ — Slow Scan Television Image
HRZ is a raw image format associated with Slow Scan Television (SSTV), a method of transmitting images over radio (shortwave or amateur radio). SSTV images are 256×240 pixels encoded as audio tones and used by amateur radio operators worldwide.
Common uses
- Amateur radio SSTV image transmission and reception
- Converting SSTV received images to standard formats
- Ham radio image archiving
- Historical radio communication image recovery
About the OTB format
OTB — On-the-air Bitmap (Nokia)
OTB is a monochrome bitmap format originally used by Nokia feature phones for sending and receiving images over SMS (picture messages). It was a standard format in early mobile phones of the late 1990s and 2000s for simple graphics like logos and ringtone icons.
Common uses
- Nokia mobile phone picture message images
- Converting legacy feature phone graphics
- Historical mobile messaging image recovery
- Early mobile logo and icon conversion
Related conversions
Other conversions available for HRZ and OTB files
Frequently asked questions
Is the conversion free?
Yes, basic conversion is completely free. For large volumes, check out our paid plans.
What is the maximum file size?
Free accounts can convert files up to 25 MB. Pro accounts up to 100 MB.
How long are my files kept?
Files are automatically deleted after 1 hour on the free plan, 24 hours on Pro.
What formats are supported?
We support over 200 source and target formats. See our complete formats page.