File Size change on saving as with SRGB color space

[mklass]

Below was all in Win Vista 64.

I took a set of photos with a Nikon D3s in Raw using AdobeRGB color space, so they were all 12-14MB each. I edited them in Capture NX2 with the same color space and saved as a JPG. At this point the JPG's were about 3-4MB, depending on cropping and resizing. Sizes were for 8x0, 10x10 or 8x12 printing at 300dpi. I then used Silver Efex Pro 2 as a standalone app to create monochrome images from the JPGs. The files now were 1-1.5MB each, still in AdobeRGB.

Next, I used PM 4.6.7 to "Save as" with no resizing, cropping or other modifications, except for converting the color space to sRGB. Quality was set to 100% All of the files grew to 4+MB. That file size isn't a problem, but I am curious why that would happen just by saving with converting the color sapce. Or does 100% quality somehow make the file bigger?

Mick

[Sven]

Hi Mick!

Having the same here. But without converting from RAW to jpg.

JPG out of the Cam: 4896x3264 pixels, 9132k Filesize
JPG saved with PM (see settings-screenshot): same dimensions, but 13902k filesize.

That's an increase of 4800k without any modification.

Details of the original one: ICC Profile: sRGB Profile
Details of the saved image: ICC Profile: sRGB IEC61966-2.1 (embedded)


[attachment deleted by admin]

[Kirk Baker]

Mick,

Below was all in Win Vista 64.

I took a set of photos with a Nikon D3s in Raw using AdobeRGB color space, so they were all 12-14MB each. I edited them in Capture NX2 with the same color space and saved as a JPG. At this point the JPG's were about 3-4MB, depending on cropping and resizing. Sizes were for 8x0, 10x10 or 8x12 printing at 300dpi. I then used Silver Efex Pro 2 as a standalone app to create monochrome images from the JPGs. The files now were 1-1.5MB each, still in AdobeRGB.

Next, I used PM 4.6.7 to "Save as" with no resizing, cropping or other modifications, except for converting the color space to sRGB. Quality was set to 100% All of the files grew to 4+MB. That file size isn't a problem, but I am curious why that would happen just by saving with converting the color sapce. Or does 100% quality somehow make the file bigger?

The sRGB profile is only 3KB in size so it isn't a factor.  The quality setting you've chosen (100%) along with Chrominance subsampling turned off will produce files that are larger than the original.  The settings you've chosen are our 'visibly lossless' JPEG settings.  If you don't mind some quality loss then either turn Chrominance subsampling on or push the quality slider down a few notches.  You should see the change in file size right next to the quality slider.

HTH,

-Kirk

[mklass]

Thanks, Kirk.

In this case, the increased file size ins't a problem. I was aiming for the best image quality. I was just surprised by the size increase.

If I'm going for the web or looking for smaller files, I usually use the subsampling option and reduce the JPG quality.

Mick