Flattening Fades Images

[Pink Peony]

I have spent an embarrassing amount of time creating high quality PNG images which I have layered into worksheets I plan to sell.  Now I need to flatten my pages.

When I use Image>Flatten, my beautiful images look faded.  The drop shadows nearly disappear altogether.  The loss of quality is dramatic.  I've tried increasing the Quality slider in the Export popup from 90 to 100 with no noticeable improvement.  

What do I do?

I am using GIMP 2.10.36.

Thank you!

[rich2005]

(12-07-2023, 04:40 AM)Pink Peony Wrote: I have spent an embarrassing amount of time creating high quality PNG images which I have layered into worksheets I plan to sell.  Now I need to flatten my pages.

Well, png is a lossless format, so high quality is a matter of perception. What you put in, is the image. You can degrade an image if you scale / rotate / ..etc but that is nothing to do with the png format.

Edit: Although you can have a 16 bit png - are you using a higher precision ?  Although I do not get a change just by flattening the layers, you can see the change in 16 bit colours (that are out-of-gamut and use PhotoGamutRGB  colour profile) compared with reducing to 8 bit Gimp RGB You can see the bright colours become muted.

   

Quote: When I use Image>Flatten, my beautiful images look faded.  The drop shadows nearly disappear altogether.  The loss of quality is dramatic.  I've tried increasing the Quality slider in the Export popup from 90 to 100 with no noticeable improvement.  
What do I do?  I am using GIMP 2.10.36.

You really need to give more information as to your work-flow. What are the properties of the layers ? Things to look for that affect the overall result - opacity - layer mode mostly. If you can give a screenshot showing layers, an example image is even better.

Image -> Flatten should not cause any change in view as you are working in Gimp. It removes the alpha channel (transparency) You can try Merge Visible Layers or New from Visible and see if that makes any difference - it shouldn't.

You are exporting with a quality setting. For jpeg bumping 90 to 100 will have no noticeable effect except on the file size.

Are you viewing these exported images and now seeing the color change ?  Different viewers can apply color management or not.

If printing expect a color change, bright colours become dull. You can emulate this in Gimp using soft proofing.

This 30 second animation showing a bit of that, layer modes / soft proofing https://i.imgur.com/FtJL0F9.mp4 - the sort of things to look out for.

[PixLab]

(12-07-2023, 04:40 AM)Pink Peony Wrote: Now I need to flatten my pages.

Who told you that? Don't listen people telling you that you need to flatten just before exporting, that's BS
You don't need to flatten to export! (as png, jpg, webp, whatnot)
As a matter of fact, flattening an image is loosing all your work (layers, mask and so on...)

Once you finished to work on your image, NO flattening > and just go to Filter > Export... input the file type (png for you) and you're good to go for what YOU SEE on the canvas, is what will be exported
I never ever flattened and always got the very right exported image, exactly what I see on the canvas with some time ~100 layers in dozen of groups or more in different levels.  

[rich2005]

Quote:...snip...You don't need to flatten to export! (as png, jpg, webp, whatnot)

Well, you just might need to flatten especially if the 'whatnot' format is PDF and your image contains a text layer. Typically for sending off to a print-shop.

Gimp still does not correctly embed a font in a PDF and when opened in a computer without that font, it is replaced by whatever is default.

Still the same old cure for that - flatten the image. (although you can also use new-from-visible)

[Ofnuts]

(12-07-2023, 11:47 AM)rich2005 Wrote:

Quote:...snip...You don't need to flatten to export! (as png, jpg, webp, whatnot)

Well, you just might need to flatten especially if the 'whatnot' format is PDF and your image contains a text layer. Typically for sending off to a print-shop.

Gimp still does not correctly embed a font in a PDF and when opened in a computer without that font, it is replaced by whatever is default.

Still the same old cure for that - flatten the image. (although you can also use new-from-visible)

Flatten isn't the same as "New form visible"... it does things because it expect the image to lose all its transparency

[Ofnuts]

(12-07-2023, 04:40 AM)Pink Peony Wrote: I have spent an embarrassing amount of time creating high quality PNG images which I have layered into worksheets I plan to sell.  Now I need to flatten my pages.

When I use Image>Flatten, my beautiful images look faded.  The drop shadows nearly disappear altogether.  The loss of quality is dramatic.  I've tried increasing the Quality slider in the Export popup from 90 to 100 with no noticeable improvement.  

What do I do?

I am using GIMP 2.10.36.

Thank you!

What is the Blend mode "style" of your layers? Default or Legacy? This can make a big difference in the rendering.

[sallyanne]

Yes I wouldn't 'flatten' you image. If you have many layers you can just merge them or export as and that will happen during the process

[PixLab]

(12-07-2023, 11:47 AM)rich2005 Wrote:

Quote:...snip...You don't need to flatten to export! (as png, jpg, webp, whatnot)

Well, you just might need to flatten especially if the 'whatnot' format is PDF and your image contains a text layer. Typically for sending off to a print-shop.

Gimp still does not correctly embed a font in a PDF and when opened in a computer without that font, it is replaced by whatever is default.

Still the same old cure for that - flatten the image. (although you can also use new-from-visible)

I can stand corrected for the PDF as I don't use GIMP to export to PDF, thus my experience is quasi null about GIMP->PDF, I would chose new-from-visible, though.