Exporting to PNG - Want small file size

[pomme27]

Hi. I am an occasional user of Affinity Designer (now Affinity Designer 2). So not an expert, and would appreciate some advice.

I am exporting an image from Designer Persona to PNG. I will ultimately use the image in an ebook. For a given pixel size (say, 1000x1400), I want to create the smallest possible PNG file (smallest in the sense of fewest megabytes). I've tried playing with a number of settings, such as changing from RGB/32 to RGB/8 and GRAY/8, and exporting to PNG-8 Dithered. But I'm still getting larger PNG files that I hope to have.

If you have any suggestions on what other settings to try, please let me know. Thank you.

 

[loukash]

What kind of image is it? A photo? A logo? A graphic?

[lacerto]

Obsolete.

[pomme27]

20 hours ago, loukash said:

What kind of image is it? A photo? A logo? A graphic?

It is a vector graphic.

[pomme27]

17 hours ago, lacerto said:

It is likely that Affinity saving routines by default embed the sRGB profile which is normally "assumed" if omitted, so just dropping the profile might give you what you expect.

Thank you. How does one “drop a profile”?

[loukash]

17 hours ago, lacerto said:

the sRGB profile

… is just a few KB. Negligible.

2 minutes ago, pomme27 said:

It is a vector graphic.

Then PNG would be the correct format if the ebook format requires graphics to be a bitmap format. (I don't know, I never had anything to do with ebooks yet.)
In Affinity, PNG export can be further optimized using the Paletized mode.

Additionally, there are 3rd party tools that will squeeze every redundant byte out of PNGs. For example, to upload PNG screenshots to this forum, I'm always "recompressing" them using the https://imageoptim.com/mac app. Can save 20 to 50 % of a regular MacOS PNG screenshot, on average about 30 %.

[R C-R]

4 minutes ago, loukash said:

For example, to upload PNG screenshots to this forum, I'm always "recompressing" them using the https://imageoptim.com/mac app.

I use it too. I highly recommend it for Mac users.

[loukash]

If there's one thing I miss from Photoshop (and Illustrator, for that matter), then it's the "Save for Web" module. In spite of all its quirks, especially with large files, it allows export options with surgical precision, including exact preview, a 2-up or 4-up.

[R C-R]

16 minutes ago, loukash said:

If there's one thing I miss from Photoshop (and Illustrator, for that matter), then it's the "Save for Web" module. In spite of all its quirks, especially with large files, it allows export options with surgical precision, including exact preview, a 2-up or 4-up.

https://www.websitebuilderinsider.com/what-happened-to-save-for-web-in-photoshop/

So apparently It was removed because it was "outdated and no longer supported by modern web browsers."

[loukash]

Thanks @R C-R.
As a side note, that article was either written by a 12-year old or by an AI bot from ca. 2005.
Or is that what's being called "journalism" today…?
Nah. Clickbait.

[R C-R]

2 hours ago, loukash said:

As a side note, that article was either written by a 12-year old or by an AI bot from ca. 2005.

Be that as it may, it is true that Adobe has declared "Save for Web" to be a legacy feature that will no longer be developed.

[lacerto]

Obsolete.

[lacerto]

Obsolete.

[lacerto]

Obsolete.

[laurent32]

Related matter :

I'd like to have your advice, since it's vector graphics, why not consider saving files in SVG ?

SVG sizes aren't they the smallest ?

[lacerto]

Obsolete.

 

[pomme27]

17 hours ago, loukash said:

Additionally, there are 3rd party tools that will squeeze every redundant byte out of PNGs. For example, to upload PNG screenshots to this forum, I'm always "recompressing" them using the https://imageoptim.com/mac app. Can save 20 to 50 % of a regular MacOS PNG screenshot, on average about 30 %.

Yes, I use Imageoptim, and have achieved good results with it. In the current instance, however, it reduces the PNG file by only 3%.

I'm beginning to think something is wrong with my vector image. Maybe I'll try recreating it from scratch. Thanks all for your comments though.

[loukash]

1 hour ago, pomme27 said:

something is wrong with my vector image

Keep in mind, even a vector image can be very complex colorwise, for example if you're using lots of gradients.
PNG is especially useful and compact only if your image doesn't contain too many color shades, i.e. for graphics, icons, logos and the like. Only then the lossless compresion can make a significant difference.

[pomme27]

Just FYI. I tinkered more with the various Affinity settings. I started with the export preset "PNG-8 (Dithered)". This defaults to a 256 color set. In my case, this produced a PNG file 1.2MB in size.

I then ratcheted down to 128, then 64, then 32, and then 16. At 16, the file size drops by 50%. I then built a test ebook using images that were exported from Affinity using the 32 and 16 color sets, then looked at the images on a 10" iPad Pro and a 6" Kindle device. The images looked fine, certainly well enough for e-reader sized screens. So I guess I'll go with that solution.

Thank you again for all your comments. You put new ideas into my head.