Keeping image quality when sharing online

[Iem1]

Hey guys,

Does anyone know how to preserve image quality when posting to facebook? I can post the image to instagram, no issues. If I post the exact same image to facebook, it appears fine on PC but gets ruined when viewed on mobile? 

I have resized the image to 2084 x 1389 and it is 3.06 MB PNG. This is what I upload to Facebook.

After I post this to facebook, this is what is actually posted (I downloaded this on my mobile from facebook and emailed it to myself):

Its a 42 Kb JPG 2048 x 1365, not sure if me downloading it affected anything, but it looks as it does here.

 

 

Any ideas? Thanks

[AstroMuni]

34 minutes ago, Iem1 said:

After I post this to facebook, this is what is actually posted (I downloaded this on my mobile from facebook and emailed it to myself):

Each website has its own ways of storing & downloading the images. A lot of the websites compress them so when you download it comes as JPGs. Also your choice of downloading on different devices could result in different sizes. A mobile phone is considered a small format device so images will be in a reduced quality to suit the device.
As an example take Flikr where a lot of astro folk store their images. I think if you upload in any other format besides PNG you end up getting JPGs when you download.

Edited March 15, 2022 by AstroMuni

[vlaiv]

Many websites optimize content that you post.

It might not seem like much - but imagine millions of people viewing hundreds or thousands of posts every day - that is massive amount of data to store and transfer and every bit of saving counts.

Best way to tackle this is to have your own website / online file server and then post only links to your own media.

Alternatively - optimize images that you post on other sites yourself. Hopefully - engine that deals with media on particular site will conclude that it is already optimized and won't waste resources on it (although there is no guarantee for that).

Mind you - most people have very small phone screens and content served to those devices does not need to be high quality, so websites optimize such images further for both speed and bandwidth savings (many people don't have flat rate access on their mobile devices but rather metered connections and appreciate optimized content).

[Iem1]

Thanks for the replies guys.

It's odd, this has only started happening to me recently (maybe 2 months or so).

Prior to that, if I tried uploading one of my astro images as is, fresh from PS, it would get stuck on 'Posting' as the images are obviously waaay bigger than FB accepts. After resizing, it would post and there was never any issue. When viewed on PC or mobile, it looked fine.

Now though, even after resizing, as you can see, it ruins the image quality when viewed on mobile while still being OK on PC. Which is a shame, as most people view FB through a mobile nowadays.

Instagram still manages fine at least!

Ah well, I was going to take my EQ6 R Pro out for first light last night now that my battery has arrived, but I would have to carry it from my flat, down the road and then up a winding 100m Elevation hill to escape the worst of bortle 5 LP. I got suited and booted, had around 30 KG - 35 KG of equipment in my rucksack on my back, the 7.5 KG tripod in one hand and my telescope case in the other, I made it down one flight of stairs and thought "This isn't going to work..."

I consider myself somewhat fit, 27 year old guy (but only 65KG myself) but I think I'd have been calling the coast guard for assistance if I had tried it

Edited March 15, 2022 by Iem1

[ONIKKINEN]

Whatsapp also is guilty of gutting images sent through it, which is why sending it as a link to somewhere its already posted or attaching it as a file is the way to go. I tried to compress images myself to see if there is a point where whatsapp agrees to send it as is but as far as i know there is none and the image always goes through some rough cuts.

27 minutes ago, Iem1 said:

Ah well, I was going to take my EQ6 R Pro out for first light last night now that my battery has arrived, but I would have to carry it from my flat, down the road and then up a winding 100m Elevation hill to escape the worst of bortle 5 LP. I got suited and booted, had around 30 KG - 35 KG of equipment in my rucksack on my back, the 7.5 KG tripod in one hand and my telescope case in the other, I made it down one flight of stairs and thought "This isn't going to work..."

I consider myself somewhat fit, 27 year old guy (but only 65KG myself) but I think I'd have been calling the coast guard for assistance if I had tried it

I find this pretty funny as i do some of this (not the hill, but 6th floor and elevator is kinda dangerous) when i escape TO a B6 or 5 zone from where i live 😀. You get used to it. Or do i just tell that to myself? Who knows.

[Lee_P]

When I need to post images directly onto sites like Facebook, I output them as longest size 2048px, and 72dpi. Seems to work ok 🤞

[Louis D]

Notice that the high frequency detail is preserved (the pinpoint city lights) while low frequency detail is compromised (the subtle sky and sea tones).  I'd guess they're using jpeg compression at a fairly aggressive setting.  The jpeg algorithm tries to preserve high frequency detail in a relatively small area at the expense of large swaths of low frequency detail under high compression.  There isn't much you can do to change how FB compresses image downloads.

[Pixies]

2 hours ago, Lee_P said:

When I need to post images directly onto sites like Facebook, I output them as longest size 2048px, and 72dpi. Seems to work ok 🤞

This  - and 24bit PNG format, which retains high frequency detail better on Facebook.

[Richard_]

13 hours ago, ONIKKINEN said:

Whatsapp also is guilty of gutting images sent through it, which is why sending it as a link to somewhere its already posted or attaching it as a file is the way to go. I tried to compress images myself to see if there is a point where whatsapp agrees to send it as is but as far as i know there is none and the image always goes through some rough cuts.

I find this pretty funny as i do some of this (not the hill, but 6th floor and elevator is kinda dangerous) when i escape TO a B6 or 5 zone from where i live 😀. You get used to it. Or do i just tell that to myself? Who knows.

If you send an image as a "document" in WhatsApp you can send the file at the full size with zero compression. It doesn't show up as a picture in the chat though so you have to open it in an image viewer or similar. 

[ollypenrice]

I don't intentionally produce images for mobile phones because I hate mobile phones 🤣 so I haven't tried this, but what happens if you resize to a much lower pixel count?  You don't need a large pixel count for a small screen display so I'd expect the downsized image to suffer less compression.

Olly

[Richard_]

10 hours ago, ollypenrice said:

I don't intentionally produce images for mobile phones because I hate mobile phones 🤣 so I haven't tried this, but what happens if you resize to a much lower pixel count?  You don't need a large pixel count for a small screen display so I'd expect the downsized image to suffer less compression.

Olly

You can see full size images on mobile phones by pinching to zoom in. Otherwise you'll be looking at a picture for ants 😁

 

[vlaiv]

10 hours ago, ollypenrice said:

I don't intentionally produce images for mobile phones because I hate mobile phones 🤣 so I haven't tried this, but what happens if you resize to a much lower pixel count?  You don't need a large pixel count for a small screen display so I'd expect the downsized image to suffer less compression.

Olly

Much like anything else these days - mobile phones suffer mega pixel craze as well.

We can see that by ever increasing PPIs that reach 400 and more.

But the thing is - even when holding phone really close - like 10" or so - human eye can't resolve individual pixels - far from it.

Normal / very good eyesight can resolve down to 1 minute of arc - or degree / 60 - so you don't really need more than 60 pixel per degree

Here is table of some phone / tablet displays (together with number of pixels per degree and usual viewing distance).

As a comparison - usual computer screen of say 24" diagonal with 1920 x 1080 resolution has ~92 PPI pixel density (2203px at diagonal of 24") and is viewed what, 20-25" away (equivalent to mobile phone with 200 PPI viewed at 10" distance) and we don't really have any issues when viewing in those conditions - we never see individual pixels of the image.

[Xiga]

On 15/03/2022 at 17:23, Iem1 said:

Hey guys,

Does anyone know how to preserve image quality when posting to facebook? I can post the image to instagram, no issues. If I post the exact same image to facebook, it appears fine on PC but gets ruined when viewed on mobile? 

I have resized the image to 2084 x 1389 and it is 3.06 MB PNG. This is what I upload to Facebook.

After I post this to facebook, this is what is actually posted (I downloaded this on my mobile from facebook and emailed it to myself):

Its a 42 Kb JPG 2048 x 1365, not sure if me downloading it affected anything, but it looks as it does here.

 

 

Any ideas? Thanks

Being a member of SGL, you are allowed to attach content (such as your lovely photo above) to your posts. I'm not sure what the total limit is per member, but it's A LOT. So there is a workaround if you want people to see the full res pic.

1. Click on your picture above. It will display in a window. Then click it again. It will then open in full res on a new tab. 

2. Now you can just share the link for this tab anywhere you like, and when the user opens it, they will see exactly the image above, in full res. 

🙂

 

[KP82]

To preserve full quality when sharing online I'm afraid you'll have to use those paid media sharing sites.

I personally use pbase.com to share all my images (not just astro, but also landscape, birds, etc.). It costs me $20 a year and allows full resolution original images.