Adobe RGB jpeg to sRGB jpeg - File size question

bystarlight

Hi,

I've been shooting in RAW for over a year now, and then saving photos to JPEGs after making my adjustments in Camera RAW.

I left the colour profile at the default setting (AdobeRGB) before saving to JPEG, so all my JPEGs are saved using the AdobeRGB profile.

I've decided I'd prefer to use sRGB instead and want to convert all my JPEGs to the sRGB Profile. To do this, I've been using the Image Processor in Photoshop CC, with the quality set to 10.

I've noticed that the file size of the original Adobe RGB profile JPEG is roughly double that of the sRGB JPEG - is this file size difference normal?

I understand that I'm converting to a smaller colour space, but half the file size for sRGB seems like a lot. I'm afraid I'm losing additional quality, other than the smaller colour space. Should I have the quality setting in the Image Processor set to 11 or 12. I've found setting it this high in the past is of no great advantage.

Thanks!

ED E

You're double compressing. Its a really bad idea as artifacts will grow.

Paulw

Ok, you have two issues here.

One being colour space. Adobe RGB contains a lot more information than sRGB.

Then you are increasing the level of compression (and removal of detail and data), by selecting the quality level 10 when you save.

Between both, yeah, file size will very much differ.

bystarlight

Thanks for the replies.

Considering I don't have most of the RAW files anymore, what's my best option here to get these JPEGs to sRGB with minimal quality loss?

magicbastarder

Paulw wrote: »

Then you are increasing the level of compression (and removal of detail and data), by selecting the quality level 10 when you save.

@OP - are you comparing a quality level of 11 or 12 with one colour space, with a quality level of 10 on the other?

bystarlight

@magicbastarder - I don't see much difference between quality level of 10 and 12 within a single colour space

magicbastarder

but in terms of file size?

bystarlight

File 1: AdobeRGB Q10 File size: 3,226 KB
File 2: AdobeRGB Q12 File size: 8,380 KB
File 3: sRGB Q10 File size: 3,478 KB
File 4: sRGB Q12 File size: 8,879 KB

* All files created from same RAW photo

magicbastarder

so the size difference is primarily due to the quality level, by the looks of it.

bystarlight

Yes. But....

Those 4 files were saved from the one original RAW file.

Then I ran File 1 AdobeRGB Q10 File size: 3,226 KB through the Image Processor, setting quality to 10 and 'Convert to sRGB' and the resulting file is 3,388 KB.

Shouldn't it be the same size as file 3 above? (3,478 KB)

DaireQuinlan

bystarlight wrote: »

Yes. But....

Those 4 files were saved from the one original RAW file.

Then I ran File 1 AdobeRGB Q10 File size: 3,226 KB through the Image Processor, setting quality to 10 and 'Convert to sRGB' and the resulting file is 3,388 KB.

Shouldn't it be the same size as file 3 above? (3,478 KB)

It's 90 KB difference, not really significant. I assume there's some metadata saved relating to the choice of colour space.

CabanSail

Can I ask what has happened to your RAW files?

Normally these are archived for any future edits as well as being very useful to show ownership of an original image.

bystarlight

ED E wrote: »

You're double compressing. Its a really bad idea as artifacts will grow.

But is what I'm doing any different from saving a JPEG twice? Isn't that double compressing also?

CabanSail wrote: »

Can I ask what has happened to your RAW files?

Normally these are archived for any future edits as well as being very useful to show ownership of an original image.

I deleted the original RAW files to save hard disk space. I'm not a professional, I'm just taking family pictures....I don't expect ownership of photos to be questioned

grogi

Paulw wrote: »

Ok, you have two issues here.

One being colour space. Adobe RGB contains a lot more information than sRGB.

AdobeRGB does NOT contain more information than sRGB. It just covers different/wider colour space.

How much information is there depends on the number of bits per pixel... 16bit per channel contains twice as much data as 8bit per channel.

grogi

bystarlight wrote: »

Hi,

I've been shooting in RAW for over a year now, and then saving photos to JPEGs after making my adjustments in Camera RAW.

I left the colour profile at the default setting (AdobeRGB) before saving to JPEG, so all my JPEGs are saved using the AdobeRGB profile.

I've decided I'd prefer to use sRGB instead and want to convert all my JPEGs to the sRGB Profile. To do this, I've been using the Image Processor in Photoshop CC, with the quality set to 10.

I've noticed that the file size of the original Adobe RGB profile JPEG is roughly double that of the sRGB JPEG - is this file size difference normal?

I understand that I'm converting to a smaller colour space, but half the file size for sRGB seems like a lot. I'm afraid I'm losing additional quality, other than the smaller colour space. Should I have the quality setting in the Image Processor set to 11 or 12. I've found setting it this high in the past is of no great advantage.

Thanks!

Don't...

What you can do is either:
- embed a colour profile in the JPGs so that the viewer knows they are in AdobeRGB and can convert the colours to the colorspace of the display device when they are displayed. This approach requires the viewer to be smart enough to perform that translation

- whenever you're sharing the pictures, convert them to sRGB on the fly.

magicbastarder

grogi wrote: »

AdobeRGB does NOT contain more information than sRGB. It just covers different/wider colour space.

How much information is there depends on the number of bits per pixel... 16bit per channel contains twice as much data as 8bit per channel.

how is the information encoded? in a bitmap, i would assume that each pixel (in an 8 bit image) contains 3 values from 0 to 255 for each channel, and then the colour space is an algorithm specified by metadata - which might imply that the pixel info does not differ between the two files. that's based on an ignorant assumption though.

grogi

magicbastarder wrote: »

how is the information encoded? in a bitmap, i would assume that each pixel (in an 8 bit image) contains 3 values from 0 to 255 for each channel, and then the colour space is an algorithm specified by metadata - which might imply that the pixel info does not differ between the two files. that's based on an ignorant assumption though.

Yes, it is exactly like that. Some formats will allow 4 channels though (4th being transparance). And on top of that you have compression - either lossless (like in PNG) or lossy (JPEG).

The colorspace is part of meta data, very often not even included in the resulting file at all.

ED E

bystarlight wrote: »

But is what I'm doing any different from saving a JPEG twice? Isn't that double compressing also?

I deleted the original RAW files to save hard disk space. I'm not a professional, I'm just taking family pictures....I don't expect ownership of photos to be questioned

If you're going to go this route, only save them once.

Remember back in the day (if you're old enough), if you were to copy a copy of a copy of a cassette the quality would be shíte. That's what you're doing.

When you make a JPEG the compression algorithm is saying "what can I throw out" (at 12 its reserved, at 6 its reckless). When you do it again its throwing out more detail and just deteriorating the images.

At 12 it'll be less noticeable, but you're degrading your images. If photography interests you, buy a NAS and save the RAWs. Great if Granny comes to you and wants a massive print of little Billy.

magicbastarder

i dump all RAWs except the really good ones, and save everything else as LZW compressed TIFFs. storage is cheap, and pruning mediocre photos is an underappreciated discipline.

at 15MB a file, you've enough space on a 1TB disc for over 50,000 photos.
if you're taking that many photos, spending a couple of hundred quid on two discs - one for backup - is a cheap investment.

Paulw

magicbastarder wrote: »

i dump all RAWs except the really good ones.

:eek:

I dump nothing. I keep all images. I have images going back to when I started taking digital photos.

Yes, it takes up a lot of space, especially when you shoot up to 2,000 images per event, shooting sport. I could cover 3-4 events in a weekend, and end up with a lot of images. But, they go on my PC, then backed up to a NAS and also to an individual external disk. I also backup the NAS to another NAS, for security. Disks are cheap enough. It's a business cost, year on year. I would probably go through 1TB of images each year, sometimes more.

All images are imported and indexed in Lightroom, but would also be stored by year, month and then event name. Makes things easier to find.

magicbastarder

Paulw wrote: »

:eek:

i'm not a pro though. and i've zero interest in going back to re-process images from a few years ago, which i was not 100% happy with in the first place anyway.

Dr_Bill

Personally I prefer to shoot in raw then process in sRGB as its pretty much standard across the board. Some more info is available here:
http://petapixel.com/2009/09/17/why-you-should-probably-use-srgb/
Storage is cheap all the same.