png-8 export settings to reduce image size

[pgrimaldi]

Hi

 

First, may you pardon me for my approximative english, it is not my native language ;-)

I am a happy user of Affinity Designer/Publisher/Photo since a couple of years.

I have switched from Adobe, and I have been earlier a heavy user of PhotoShop/Illustrator/InDesign (20 years) until the monthly fee.

My question is about the presets of png/gif export on an image in Designer : in my webdesign workflow, I use a vector program to create tables or charts and I export them in jpg/png/gif ; I need to keep little weights.

I have noticed that such images generated from Designer are often heavier than from PhotoShop ...

My question: is it possible to access fine parameters like in PhotoShop?

In PhotoShop it is possible to choose a color reduction method (perception, selective, adaptative, ...), and the dithering method (without, diffusion, pattern, ...).  In Designer, the only choice for png is png-24 or png-8 (with diffusion)... and the expert window don't have these parameters

I join screen captures of PS : under the "1." the export parameters of PS ; under the "2.", you can see that when exporting an image with and without dithering, there is a significant difference : in my example, setting the dithering to "none" gets an image from 310,1K to 165,4K (all other settings are unchanged).

I would like to know if it is possible to do that with the Affinity Suite? Or maybe make this suggestion to the development team ;-)

 

Best regards,

Patrick

[Ulysses]

15 hours ago, pgrimaldi said:

I would like to know if it is possible to do that with the Affinity Suite? Or maybe make this suggestion to the development team

The short answer is “Yes.” However, the Designer and Photo interface will not be as detailed as what you see in Photoshop, and it won’t offer as many options. 

In Designer and Photo, when telling the software to export an image, you should see a switch to use “Palettized” colors. Once this switch is activated, you now gain access to two important options: 

1. You can choose the Palette of colors you want — Automatic, Web, Grayscale, etc. Automatic seems to be a palette generated from the colors contained in your image.
2. If you choose an Automatic palette, you can then also choose your Colors — how many different colors you wish this palette to posses. The range will be from 256 down to 2. 

You can watch Designer/Photo calculate the expected file size based upon the options you choose. The savings can be significant. But as always, you must choose a desirable balance between file size and image quality. 

[pgrimaldi]

5 hours ago, Ulysses said:

The short answer is “Yes.” However, the Designer and Photo interface will not be as detailed as what you see in Photoshop, and it won’t offer as many options. 

In Designer and Photo, when telling the software to export an image, you should see a switch to use “Palettized” colors. Once this switch is activated, you now gain access to two important options: 

1. You can choose the Palette of colors you want — Automatic, Web, Grayscale, etc. Automatic seems to be a palette generated from the colors contained in your image.
2. If you choose an Automatic palette, you can then also choose your Colors — how many different colors you wish this palette to posses. The range will be from 256 down to 2. 

You can watch Designer/Photo calculate the expected file size based upon the options you choose. The savings can be significant. But as always, you must choose a desirable balance between file size and image quality. 

Thank you Ulysses for this quick answer

But I can't find any option to deactivate the dithering: this could help to decrease file size even more (with some local color changes of course), because of big surfaces with one color.

In my workflow, I'll have to use Designer to layout my figure, then export to png-24 or psd, open with PhotoShop and export to png-8 with non-dithering ("Sans tramage") settings

Regards,

Patrick

Edited June 26, 2020 by pgrimaldi

[Ulysses]

33 minutes ago, pgrimaldi said:

But I can't find any option to deactivate the dithering: this could help to decrease file size even more (with some local color changes of course), because of big surfaces with one color.

This is correct on both counts. If there were a way to deactivate dithering, it would help reduce file size for this candidate of image. However, I do not know of a way to do so in Affinity Photo. 

One thing you could try before saving the file is apply a Posterize adjustment layer. This *might* reduce the palette size, thereby also saving file size. Let me know if this theory works at all. 

[Zmip]

Please add this as high as possible on the feature request list. It's probably low hanging fruit, because the image library used probably allows the dithering algorithm to be on or off. It should not default to "on", just as @pgrimaldi points out in this topic.

Like the OP, I'm ending up with way too big GIF and PNG exports from Designer and Photo. It seems there aren't many tools that offer the fine-grained control over PNG output as Photoshop does (tried ImageOptim (free) and GraphicConverter).

[TravisL]

I'd also really like to be able to turn off dithering - or better yet, allow a slider like Photo Demon and Adobe Photoshop has done where you can specify the amount of dithering so you can tailor it to each image. Being able to make images as small as possible while keeping them looking good is a very important part of exporting images for web.