[FEATURE] fit-to-screen mode, resampling filters, and scroll delay config

[MisPilasNoCargan]

Hi, I really like your program and I’ve been using it for a few weeks, and I would love it if you could add a few things that would make the program feel perfect for me.

Could you add a viewing mode where the image fits both horizontally and vertically? Sometimes I want to browse an illustration book, but since all the images are different sizes, only in some of them can I go to the next page using the mouse wheel, while in others I have to scroll.

Another thing, have you thought about adding different resampling filters? That would help a lot with image viewing in relation to the previous point, since images that are too large do not look very sharp in that mode.

And lastly, I use a program called SmoothScroll that adds custom smoothness to scrolling. When I use it in your program and scroll to the end, it sometimes jumps to the next page because there is nothing stopping it. Is it possible to add a setting to change the amount of time the page is held before moving to the next one?

If you could just do the first point, I'd be happy. Thanks.

[binarynonsense]

Hi!

Thanks for the feature requests, here are my initial thoughts:

• A "Fit Page" mode is something I´d be interested in adding. I don't know how easy it'd be to add given how I have things arranged right now, especially in double page mode (could be easy, could need some changes), but I'll definitely add it to my TODO list to at least try to implement it one day.

• You mean when a comic book / art page the image is downsized to scale it down to fit, it looks maybe blurry and you'd want it to look sharper? I seem to be less sensitive to this as, with the comics and books I usually read, I'm happy enough with how they look even if I make the window smaller. Only thing may be the texts, which end up unreadable if you make it small enough but I don't know if that's what you are experiencing / want to fix (and I guess that even with a different algorithm it's something bound to happen if you make them small enough).
  Have you tried the filter system I recently added in the preferences? (Comic Book Reader > Filters) to create one? maybe creating one playing with the contrast, brightness or the levels could help (once created, to apply it you just go to View>Filter). Edit: I'm not sure if there's any combination of the values that'd help with this, but it's just an idea to try.
  In terms of purely downsampling algorithms, from my quick initial research (it's the first time I look into this topic): I'm a bit limited by what the rendering engine of chromium allows, which is what the framework I use is based on, and what manages how images are shown, but maybe I could explore things like the CSS image-rendering property, which has an option for a sharper algorithm (webkit-optimize-contrast) instead of the default, which I think is bilinear. Thing is that property doesn't have that many options and you can't select one for downscaling and one for upscaling, and from what I read there's not really a great one among those for downsampling art anyway (not really sure webkit-optimize-contrast would help)... So i don't know if anything useful will come from it or if it'll accomplish what you want, but I'll try to investigate more some day if I can. This one is a "maybe, not sure".
  Edit: I just tried webkit-optimize-contrast and looks basically the same, the only noticeable one is pixelated but that looks bad, so I don't think image-rendering will be an option.

• Changing pages using the scroll wheel doesn't work by "the amount of time the page is held", it just checks if an end has been reached during the current scroll, once you reach the end of the page, the next time you scroll in that same direction the page changes. Maybe I could add a minimum, configurable, time between reaching an end and allowing changing the page, it would ignore the scroll until that time passes, would that achieve what you want?

[MisPilasNoCargan]

1.- Thank you.

2.- For example when the image is too large and has those grid-like patterns. When it's at 100% it looks fine, but when you view it from a distance those patterns appear like in the photo.

3.- Yes! That would prevent the page from jumping to the next one during a fast scroll. It would be great if it were configurable, so users who don't like that pause can reduce it and keep the current behavior.

[binarynonsense]

I think what you are describing is a moiré pattern, I remember it happening to me while creating art with halftones and saving the images to smaller sizes for example. From what I'm reading it also happens when downsampling images with many algorithms, which is why it's probably happening in some situations in ACBR (maybe some manga or black and white comics?) as, from what I can gather, chromium uses bilinear by default. Also, the fact the the zoom in ACBR needs to adapt to any size maybe brings noninteger scaling into play, which causes moiré, although the bilinear algorithm should help with this from what I read... I need to learn more about all of this :)

As I said I'm a bit limited by what I can do with my current setup but I'll try to look into it to see if I figure out some improvement that doesn't require changing the way I manage page scaling or worsens speed. I haven't seen anything too promising for now but I'll keep at it when I have some time, as there are some techniques I want to at least try, but right now I can't make any promises about being able to improve this.

It would be great if you could share a real image, not just a dot pattern, where you have experienced this in ACBR so I can see it in action in the program and use for testing (if you load a book with a page with this issue in ACBR, you can right click in the image to show an option to save as image, that may be helpful to get one; and then you can open that saved image in ACBR after that before sharing it with me to make sure it still shows the pattern when it's downsized).

[MisPilasNoCargan]

No problem :)

I tested the sample image in Firefox and saw pretty much the same thing happening with ACBR, so no need to stress over it.

[binarynonsense]

Thanks for the test file! Yeah, I see the pattern when reading this in Firefox too, I've seen it in the past with images with halftones and things like that (Edit: in browsers and other readers or image viewers, I don't think I tested any manga using them with ACBR so I didn't think about this problem until now). For the moment at least, I'll mark this feature as out of scope, I may not be able to do anything about it but, if I figure something out, now I have an image to test it with .

The other two features (Fit Page scale option and change page scrolling delay), on the other hand, I have added to my TODO list to try implementing some day (my usual disclaimer: I don't know if I'll be able to add them, although I'm confident, or when I'll be able to work on them, as there are some bug fixes and some restructuring of the image processing code I have planned, among other things, that I need to do first and I can only work on ACBR from time to time, so no promises :) but I'll let you know here as soon as I have some news).