"Flip Both" affects color in RAW8 mode

A place to report problems and bugs in SharpCap
Forum rules


If you have a problem or question, please check the FAQ to see if it already has an answer : https://www.sharpcap.co.uk/sharpcap-faqs

Please also read about Troubleshooting USB Issues before posting.

*** Please do not post license keys - please report any problems with licensing to 'admin' by private message ***

Please include the following details in any bug report:

* Version of SharpCap
* Camera and other hardware being user
* Operating system version
* Contents of the SharpCap log after the problem has occurred.
[If SharpCap crashes, please send the bug report when prompted instead of including the log]
Post Reply
larryh
Posts: 9
Joined: Sat May 27, 2017 8:57 pm

"Flip Both" affects color in RAW8 mode

#1

Post by larryh »

Hi Robin,
I was collecting images from the lunar eclipse last night and after a meridian flip I decided to use the "flip both" option to get the image oriented the same as before the meridian flip. Today I discovered that all of the images after I selected "flip both" did not debayer correctly in Planetary Image PreProcessor (PIPP). I normally use RGGB to debayer the RAW8 images, however, I found that the images were blue when I did so. Thankfully it turned out that if I used BGGR I got the correct color. Here is an example .png file along with the camera settings I used:
Moon_00040.png
Moon_00040.png (835.83 KiB) Viewed 1394 times
Moon_00040.CameraSettings.txt
(715 Bytes) Downloaded 126 times
I don't know if there is any similar effect for other image formats or when selecting other flip options.
Thanks!
Larry
User avatar
admin
Site Admin
Posts: 13173
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: "Flip Both" affects color in RAW8 mode

#2

Post by admin »

Hi Larry,

that is as designed – when you turn the image round or flip it in either or both directions, the sequence of coloured pixels at the top left-hand corner changes. SharpCap tracks this internally when you flip the image and writes the correct value into the image meta data. Unfortunately not many Astro processing applications read the image meta data from fits files concerning the Bayer pattern, so it's necessary to make these changes manually when processing.

Think of the image pixel layout being like this and then imagine what it looks like when you flip it either upside down or upside down and horizontally.

Code: Select all

RGRGRGRGRG
GBGBGBGBGB
RGRGRGRGRG
GBGBGBGBGB

Cheers, Robin
User avatar
turfpit
Posts: 1779
Joined: Mon Feb 13, 2017 8:13 pm
Location: UK
Contact:

Re: "Flip Both" affects color in RAW8 mode

#3

Post by turfpit »

Well done Larry for working it out.

Take a simple 2x2 grid RGGB:

RG
GB

Flip it top to bottom gives:

GB
RG

Flip left to right:

BG
GR

Hence matrix becomes:

BGGR

For anyone meeting this for the first time see viewtopic.php?f=35&t=254
The doc that keeps on giving - > 3500 views and > 500 downloads.

Dave
Post Reply