topic Re: Mosaic color balance in Data Management Questions

Mosaic color balance

MohammadDashti — Thu, 19 Jan 2012 11:14:27 GMT

Hello,

I have to create a mosaic image of the coastal strip.
I have 20 images from Geoeye-1 acquired on 3 different dates.

if I mosaic images form the same date which cover smaller area the product image is good.

However when I mosaic all the 20 images I got very bad colors.

if I optimize the stretch for a specific area the other area get greenish or purplish.
if I set the stretch for the whole mosaic I get bad color all around.

here is the result ([ATTACH=CONFIG]11299[/ATTACH])
I tried all the available color balance methods available in ArcGIS but the result is always the same.

here is my methodology

1- create geodatabase
2- create new empty mosaic dataset
3- add images to the mosaic dataset
4- edit footprints
5- build boundary
6- build seamlines
7- run 'color balance tool'
8- generate overview
9- export to raster

is the problem in my workflow?
or the only problem is the different acquisition dates?

is there a way to fix the color problem?

thanks in advance for any reply or read,

Mohammad Dashti
GIS & RS Tech

Re: Mosaic color balance

MohammadDashti — Sun, 12 Feb 2012 08:38:30 GMT

Any Comments?

Re: Mosaic color balance

DanPatterson_Retired — Sun, 12 Feb 2012 11:54:34 GMT

Did you rule out the procedures in the help file?

Re: Mosaic color balance

JieZhang — Mon, 13 Feb 2012 14:11:42 GMT

Hi dasmy004,

Your workflow seems correct to me.

But from the screenshot you attached here, I can tell either the seamlines were not generated correctly or they were not used during color correction. Would you mind give another screenshot of your seamlines feature class? You can turn on the seamlines layer as one of the mosaic dataset's sublayer in the ArcMap table of contents.

If the seamlines were not generated correctly, you can remove the seamlines by right click on the mosaic dataset in the catalog window and choose "Remove->Seamlines" and then rebuild the seamlines. Also you need make sure the mosaic dataset is using the "seamlines" mosaic method as the default mosaic method when you export the mosaic dataset to a raster dataset.

Jie

Re: Mosaic color balance

MohammadDashti — Tue, 06 Mar 2012 09:45:37 GMT

I found that because the images were acquired at different date, and probably because of different atmospheric effects of the images, the color will not be balanced automatically.

I decided to divide the area into three section trying to keep images from the same date in in the mosaic data set.

Color balance did a better job but still did not produce a seamless image.

Jie,
I do not know why you think seamlines could cause color balance problem. I regenerated them to be sure and did not get different result. here is the seasmlines for the three mosaics.

[ATTACH=CONFIG]12438[/ATTACH]
,Regards
Mohammad Dashti

Re: Mosaic color balance

JieZhang — Tue, 06 Mar 2012 15:05:22 GMT

Hi Mohammad,

Seamlines could help the display of the mosaic. If you use the seamline mosaic method plus color balance, it will look better than just the color balance plus the default north west mosaic method.

Your previous screenshot shows steep edges between images, it indicates either the mosaic method is not set to use seamlines or the seamlines weren't generated correctly.

Seasonal changes between images could have impact on color balance result. Also you can watch out for cloud cover or snow, sudden increase of the cloud cover between images could also result in imperfect color balance.

Hope it helps.

Jie

Re: Mosaic color balance

MohammadDashti — Wed, 07 Mar 2012 08:25:16 GMT

thanks a lot jie

I eliminated zero, nodata, cloud cover and most of the water, and separated imaged with huge color differences due to seasonal changes in separate mosaics.

I also noticed that I get worse results when I mosaic pre pan-sharpened imagery, and that color balance works better on the original images.
Maybe I should pan sharp after mosaic, but that will consume enormous desk space and time, and might fail because of the large data set

Please look at my other thread http://forums.arcgis.com/threads/52303-Mosaic-Dataset-_-methods-and-problems?p=178755#post178755

Regards,
Mohammad