Wikipedia:Reference desk/Archives/Science/2023 May 31

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May 31

Copernicus Open Access Hub

I was exploring the Copernicus Open Access Hub and was wondering how do you get the images and data from the satellites to usable images like the one's at image of the day. I was look at the IMG folder in the Granule but the files are jp2 and when converted to jpg are very dark.

PS: Here's a tutorial on accessing the images. PalauanLibertarian^🗣️ 13:56, 31 May 2023 (UTC)

The article JPEG 2000 shows comparison of .jpg and .jp2 files for the same source image and there are no obvious brightness differences. I downloaded a Copernicus image file that arrived as a .jpg with 24 bit/pixel "True color" depth and little or no compression, resulting in a large and relatively slow loading file. The free image editor IrfanView is useful for converting between .jp2 and .jpg. It can display a histogram of pixel intensities and it offers a range of brightness, contrast, tint, and gamma modifications. Philvoids (talk) 21:38, 31 May 2023 (UTC)

@Philvoids How did you download a .jpg. I thought all the img's were jp2's. I tried downloading some of them and converting them to jpgs but they are just black and white. Example1 Example2. PalauanLibertarian^🗣️ 01:19, 1 June 2023 (UTC)

Wow those converted images are a mess! My one test was to use the Download image button beside a featured .jpg (not .jp2) image on the Copernicus website. I suggest you check that you have an image editor that can properly convert .jp2 <--> .jpg in both directions. Here's a wide selection. Philvoids (talk) 14:00, 1 June 2023 (UTC)

@Philvoids Wierd. I used IrfanView to convert them. Where did use find the "featured images" in the open access hub. I know they have color images on copernicus.eu but I am looking at the Open Access Hub. PalauanLibertarian^🗣️ 15:34, 1 June 2023 (UTC)

I confess that I merely "leafed through" the Open Access Hub to see any image that I could download without registering. The image happened to be of Brac Croatia and not very helpful to you since it is an unproblematic .jpg. Sorry! Philvoids (talk) 16:11, 1 June 2023 (UTC)

Ok, it's fine. I found out you need like GIS software and you use certain color bands to create the image. Here's the brac image I believe you were looking at. PalauanLibertarian^🗣️ 21:29, 1 June 2023 (UTC)

Yes that's the image. Can you explain what you found or show a correct conversion? Philvoids (talk) 23:07, 2 June 2023 (UTC)

Here's how it works. As you can see here, the Sentinel-2 has 12 spectral bands. We need the Red, Green, and Blue (RGB) ones to make a color image. By themselves, an individual band image won't look good. So you create a raster with those three images. Basically stacking them on top of one another. Then you will see the natural color. You need a GIS software to do this, like ArcGIS or QGIS. PalauanLibertarian^🗣️ 01:28, 5 June 2023 (UTC)