Canon EOS 77D Instruction Manual page 155

1
1 is the raw image data before it is made into 73 or other images.
1 images cannot be viewed on a computer without the use of
software, such as Digital Photo Professional (EOS software, p.488).
However, you can perform various adjustments on them that are
impossible with other image types such as 73. 1 is effective when
you want to precisely adjust the image yourself or shoot an important
subject.
1+73
1+73 records a 1 image and a 73 image with a single shot. The
two images are saved to the card simultaneously. The two images will
be saved in the same folder with the same file numbers (file extension
.JPG for JPEG and .CR2 for RAW). 73 images can be viewed or
printed even with a computer that does not have EOS software
installed.
RAW Image Processing Software
To display RAW images on a computer, using Digital Photo Professional

(DPP, EOS software) is recommended (p.488).
Previous versions of DPP Ver.4.x cannot process RAW images taken with

this camera. If a previous version of DPP Ver.4.x is installed on your
computer, obtain and install the latest version of DPP from the Canon Web
site to update it. (The previous version will be overwritten.) Note that DPP
Ver.3.x or earlier cannot process RAW images taken with this camera.
Commercially-available software may not be able to display RAW

images taken with this camera. For compatibility information, contact the
software manufacturer.
3 Setting the Image-Recording Quality
1 image
73 image
File number
0001 . CR2
0001 . JPG
File extension
155