To backup or create a read-back of your Mediatek smartphone ROM that can be flashed on another device via SP Flashtool, follow the instructions here carefully.
If you have any questions, do not hesitate to ask in comments section.
How to Create MTK ROM Read-back, Backup
Launch SP Flash Tool and load the created scatter file by clicking scatter-loading button. After loading scatter file click Read-back tab.
Click Add then double click in the File column of the added entry.
Select location where you want to save read-back file and click Save.
See linear_start_addr of last partition in scatter file. Input the linear_start_addr address in Readback Length.
Note: If this length doesn’t work, try adding linear_start_addr of 2nd to the last partition or CACHE partition.
Turn off your phone, remove battery for few seconds then insert battery (don’t switch on).
Click Read Back button in SP flash tool and connect your phone to PC via USB cable.
Once read-back is complete, Readback Ok message with green circle will popup. You can now disconnect your phone from PC.
Launch MTKdroidTools and connect your phone via USB cable. If MTKdroidTools doesn’t detect your phone, navigate to Settings -> Developer Options and select USB debugging on your phone.
If there is no Developer Options in Settings, go to About phone and tap Build number 7 times to enable Developer Options.
In MTKdroidTools click root, backup, recovery tab.
Click To process file ROM_from Flash Tool.
Read also: How to backup Spreadtrum (SPD) Firmware
Select the Read-back file. Should be ROM_0, ROM_1, or something like that.
Click No to cancel CWM recovery creation popup.
When asked to select recovery.img file, click Cancel
Wait for the read-back extraction task to complete.
Navigate to MtkDroidTools/backups folder to find your backup file. To be sure that the backup completed without fault, compare the size of system.img file with /system folder. If they are the same, your backup is good for use.
Thanks to DroidGyan.