AP: Howto identify the bit depth of a image?

[michabbb]

hi,

 

photoshop shows me something like "indexed" in the layers and correct infos about color depth, but AP shows me for a

8 bit and 24 bit the same info. the atteched image is 24bit, bit AP shows me in the info area this: 

 

 

so i cannot identify a 8bit from a real 24bit...

 

i am very confused, is this a bug or am i just blind to see the correct infos ??

 

thanks,

micha

[Alfred]

Welcome to the Serif Affinity Forums, micha. :)

 

The "8" in "RGB/8" refers to 8 bits per colour channel; i.e. 8 for red, 8 for green and 8 for blue. So an "RGB/8" image is 24 bits per pixel.

[michabbb]

thanks for the quick reply... okay, i guess i have to ask in a different way.

the following image (attched) has indexed colors, but when i open both images (8bit and 24bit) in AP, i don´t see any difference.

how do i know that this image (in this posting) has indexed colors ??? because AP always shows RGBA/8.

 

thanks a lot,

micha

[michabbb]

i forgot to add the image in the first posting. windows shows me different bit depths:

 

 

but when i open both images in AP i don´t see any difference, but of course, there is a differnce !

the 8bit image has indexed colors, but i don´t know howto identify this in AP.

 

thanks for any help!

micha

[Alfred]

Thanks for both the clarification and the missing image! When I opened the first (8bpp) image in IrfanView, I could see that it uses a palette of 256 colours; now that you have provided the second image, the difference is clear. I agree that Affinity Photo needs to distinguish between the two different types of PNG image.

[michabbb]

dear alfred, thanks for your feedback. i switched from PS to AP because i thought, the most simple things are implemented here. i guess even GIMP does show you a difference, so in this special case, it's either a bug or if this is wanted, AP became useless to me. what shall i do with a program that is unable to show me the most important infos of an image  :(

 

dear serif, please comment this. thanks!

 

btw... the latest beta acts the same....

[Fixx]

AP has only RGB, greyscale, LAB and CMYK colour spaces, in 8, 16 and 32 bits (not all bit depths in all spaces). No indexed colour, no bitmap. All foreign colour spaces will be converted to RGB. Therefore there is not much use to try to check indexed colour state within AP. Active AP colour space can be checked in Document>Colour Format.

 

There are requests that indexed and bitmap spaces would be included in AP but I guess it may take time as they are quite different from normal ones.

[michabbb]

i understand, but as a web developer you need to handle a lot of different types of images and very often, it´s important "to know" what you are dealing with, it's very frustrating to realize, these very important (maybe not to everyone) colour spaces are missing here...   :(

 

but thanks for clarification 

[R C-R]

michabbb,

 

As I am sure you know, all that really matters for web page rendering is file size vs. image quality. And since no web browser (that I know of) can display native format Affinity files, you must export from Affinity to a web-friendly file format to use the images on a web page. At that time you can choose a lossy format like JPEG & set the quality/file size tradeoff, or maybe choose GIF & set the index colors for that. Almost everything will be displayed in current browsers in RGB color space & probably the sRGB color profile anyway, most likely interpolated to adapt to the device's native pixel resolution (or whatever "actual size" the browser is set to or defaults to using), so there is really not much point in worrying about the "missing" color spaces or bit depths (not the same thing) in Affinity.

 

Of course, it matters more for images  downloaded from a web server, but that is a different subject & there are different ways to deal with that.

[michabbb]

the problem is "knowing". you are right, but just only in your described scenario.

 

let me explain my real problem here:

 

there is a very famous online shop (oxid), which takes very large images (as a master image) to resize them, as the shop config needs them, i.e. thumbnail, gallery image, product image and so on... 

the shop (php) does the resize on its own. so.... someone came to me and says "hey, why are these images so buggy, the lines look very 'fragmented' " - so i take the raw image to find out, whats going on. i said "hey, i don´t know what the problem is, sorry".

so someone else took another (master) image and compared it with the "buggy" one. i wasn´t able to see any difference, but the person who was using photoshop, did see this "on the first view" !!! because photoshop tells you in the top and on the layers,

if the image has indexed colours. so... end of the story...  i am a fool, because i don´t see anything, and cannot solve a problem, that is based on different types of colour - and i never come to the idea, to use simple windows -> file -> properties -> bit depth.

so, with affinity photo i am not able to debug different images, because of these missing colour spaces.

 

and this for, when i have to analyse an image, is very frustrating to realize, that i have to use another program, to see all important informations of an image. that was not the idea, when i bought AP.

 

but anyway, this was a long and stupid journey for me, and as long as these colour spaces are missing, AP is not a tool for developers who have to deal a lot with images, which come from different sources and need to be debuged.

 

i know, my special case here is not the usual use case for AP, and most people will tell me: AP is not for debugging, its for creating images. but anyway, i personally expact a photo program to be able to handle ALL images and therefor ALL colour spaces.

a professional would never use an editor, which only able to handle TXT files, bot NOT BAT files... and more worse... if the editor would turn BAT into TXT without any infos... this is fatal..... (it`s only a stupid example, i guess you got me)

 

so... i hope serif will add these colour spaces someday....

[R C-R]

michabbb,

 

What you are calling missing color spaces are not color spaces -- you are talking about palettes for indexed color & bit depth for the rest of it. As Fixx said, Affinity supports the four most common color spaces at 8,16, & 32 bit depths. There is nothing "buggy" about how Affinity handles other bits depths, nor is an image at any given bit depth inherently buggy. For bit depths less than 8 bits per color, you should be able to identify them from the histogram panel.

 

You may want to check out a few online tutorials if any of this is unclear. For example, this Cambridge in Colour page discusses bit depths, & this three part one discusses color management, including color profiles, color spaces, & color conversions.

[Fixx]

While less than 8-bit colours are not true colour spaces, they in practice behave like ones in common work flows. I though said they are "quite different".

 

Truth is AP is NOT very well adapted to low bit depth work. There are no "bugs", just missing features.

[michabbb]

I am not a designer, so sorry if I only copied things, other people said. For me it does not play a role if these missing features is called "colour spaces" or whatever, wo don't need to define this and make a science of it, because it does not help me, AP has missing features here and this is (in my special case) very stupid, because next to someone, who is using photoshop, I am looking like a newbie.

And if you earn money with your work, that's not acceptable.

[R C-R]

michabbb,

 

Earlier you said you did not know how to identify indexed colors in AP. The Cambridge in Colour tutorial explains how to do that in any app with a histogram display. That includes AP. You do not need Photoshop for this, just a basic understanding of color formats, which those tutorials provide. If you do not want to look like a newbie, this is knowledge you need.

[Fixx]

Indexed colour and RGB image files may have identical histograms. Histogram does not help here.

[michabbb]

@R C-R , i am always happy to learn, can you please provide me a link to the tutorial you are talking about ? i will check if in my case Fixx is right or not ;)

[R C-R]

Indexed colour and RGB image files may have identical histograms. Histogram does not help here.

Indexed color histograms have characteristic narrow spikes at each index color, separated by flat troughs with no pixels, similar to what you see when you posterize a full color file. AP's histogram window could be bigger, but even at its small size you can see that at a glance. You can also use AP's swatches panel to create a document palette to see all the colors the file contains.

 

While it is possible that a full color image file would also include just a few colors & have a similar looking histogram, it doesn't really matter -- either way you have all the colors the file contains. If you are exporting the file you won't lose any of them unless you either choose a lossy format or choose an export option for a file type that supports palette reduction to lower than 256 indexed colors & you choose to use that. For web pages when file size is a concern, the obvious choice is GIF (which always uses indexed colors) but you can also use JPEG or PNG with a reduction to a 256, 128, etc. color palette.

 

It is true that AP is not well adapted for working with low (less than 8 bit) color depth formats, but those formats are poorly suited for photographs or other continuous tone images to begin with, preclude the use of gradients & most filers & adjustments, & impose other limitations most Affinity users would prefer to avoid. If you really need that, you should choose some other app, ideally one purpose designed for that kind of work.

 

@michabbb: I already provided links to the Cambridge in Colour tutorials in an earlier post. There are many others on the web but I believe the Cambridge stuff is among the best, offering brief yet reasonably complete overviews in an easily accessible format. There is some "science" to it that you will need to learn -- color spaces are mathematical abstractions that try to model human visual perception -- but the basics are not hard to understand.

 

Once you do, you will be able to drop terms like "PCS" into your conversations with clients & colleagues & impress them with your deep knowledge of the subject (which they probably don't have).  :)

[michabbb]

@R C-R: thanks  B)

[Fixx]

Here is RGB image with histogram:

 

 

And here is indexed colour image with histogram:

 

 

They are identical. In practice if you save them to png there should be no difference how they behave in web environment, also size should be almost the same. Some technical situations may cause problems, so it would be nice if there was a way find out the exact colour model of the document.

[michabbb]

@Fixx 100% ACK

 

as I already explained at the beginning, *knowing* what's in front of me, is all I want.

[R C-R]

Fixx: What kind of "technical situation" could cause problems if both images were using the same RGB/8 color model? In real world, practical terms, what would you gain by knowing that one is using indexed color & the other is RGB/8?

[michabbb]

@rcr I already explained, very detailed, why this became a real world problem for me, the reason this thread got started in the first place. ----> https://forum.affinity.serif.com/index.php?/topic/43251-ap-howto-identify-the-bit-depth-of-a-image/?p=216130

[R C-R]

michabbb, I have not forgotten about your earlier post or your problem. Changing apps or waiting for new features in Affinity will not solve it. Learning more about color spaces, image file formats, & the part they play in getting the results you & your clients want will.