Re: Is Add alpha channel really necessary?
[about not making background special wrt alpha] What do you think? YES please. this is simply annoying. I would even go as far as removing the "Add Alpha Channel" option from the menus, and suggest that the prefered method to add transparency to an image that has only one layer is to add a new layer, even if it is deleted immediately. This is not worse than the method used now by some users (duplicate and delete the original) and I think that it would be more intuitive to some users. I would say, simply make a layer by default have alpha always... I know I know it's more memory for that 0.001 % of cases where people start with one background layer and stick to one the whole time, without using alpha I suspect that there is a very good reason for having a default background layer without alpha -- although I'm not sure I know what it is ;-) I seem to remember that this is the way PhotoShop does it (I'm going to check on this later tonight), and that would probably be a good enough reason not to fiddle with this. However, I'm thinking about what usability reasons might be invoked for not changing this behavior of layer operation. Here's one line of thought... There are times when having no alpha channel is a very good thing, and this is why the function Flatten Image exists. Since there are file formats that don't support transparency, it is important that the user be able to decide when, and how to flatten the image (i.e., remove the alpha channel). Furthermore, imagine you are a user that doesn't make use of layers or transparency. Under these conditions, having a default background layer with no alpha channel is not a bother but a convenience. In fact, there may be other reasons not to change this behavior that I haven't thought of. I would suggest that before jumping to change this traditional behavior that it undergo some serious examination. If PhotoShop does it this way, we should try to understand why before changing. Carey Bunks Dr. Carey Bunks Senior Scientist BBN Technologies 70 Fawcett St, 15/2A Cambridge, MA 02138 tel: 617-873-3028 fax: 617-873-2918 email: [EMAIL PROTECTED]
Re: Is Add alpha channel really necessary?
... It should be easy add an alpha channel to the background layer as soon as a second layer is added to the image. Is there a reason why this should not be done automatically? I think that it would make things easier to understand for the user. Making the background layer "special" is not very intuitive. ... What do you think? NO, please. `Special' background layer maybe isn't very intuitive, but automatical promoting has the same problem: it's based on a side-effect and it's not intuitive too. We would have to explain (in some new Gimp tip) why properties of background layer chage when you add second layer. Layers _definitely_ shouldn't be changed by any action on other layers. Adding automatically alpha channel to everything seems to be a better solution, but imagine you open some image in a not-alpha-capable format, change a few pixels and try to save it and Gimp will start asking you about exporting, and flattening it. That's not anything I would call intuitive behaviour. The only good solution is probably to make `Add Alpha Channel' more intuitive. The user should _see_ the background layer is special---lacks something---and there must be some obvious way how to add it. (But is there an obvious way how to manage this?) Yeti Hi! I'm a .signature virus! Copy me into your ~/.signature to help me spread!
Re: Is Add alpha channel really necessary?
On Tue, 16 May 2000, David Necas wrote: Making the background layer "special" is not very intuitive. ... What do you think? NO, please. snip The only good solution is probably to make `Add Alpha Channel' more intuitive. The user should _see_ the background layer is special---lacks something---and there must be some obvious way how to add it. (But is there an obvious way how to manage this?) How about changing the layers dialog box so the background layer appears solid and the layers with alpha have a gradient-to-checker background. This way one can tell at a glance if a layer has alpha or not. This is hard to describe. If anyone is interested I'll mark up a screengrab of how this might look. -- Jon Winters http://www.obscurasite.com/ "Everybody loves the GIMP!" http://www.gimp.org/
Re: Is Add alpha channel really necessary?
On Tue, 16 May 2000, Jens Lautenbacher [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] (Raphael Quinet) writes: I would even go as far as removing the "Add Alpha Channel" option from the menus, and suggest that the prefered method to add transparency to an image that has only one layer is to add a new layer, even if it is deleted immediately. This is not worse than the method used now by some users (duplicate and delete the original) and I think that it would be more intuitive to some users. I would say, simply make a layer by default have alpha always... I know I know it's more memory for that 0.001 % of cases where people start with one background layer and stick to one the whole time, without using alpha Hmmm... No, I think that it makes sense to create single-layer images without alpha. If you are working mostly with image formats that do not support alpha (i.e. JPEG, BMP, PPM, PCX) or if you are not interested in having transparency anyway, then you probably want the Gimp to behave as most of the old painting programs behaved: no layers, no transparency, and "clearing" an area means to fill it with the background color. It also saves some memory if you are using the Gimp to do some color corrections or simple retouching on huge images (e.g. your photo collection or some scanned images). But on the other hand, as soon as you start working with multiple layers, then you need to work with transparency (and to understand the concepts involved). That's why I would promote the background layer to RGBA when you add a second layer. I still haven't found a good reason to keep the background layer "special" when the image contains multiple layers. If the only reasons are historical or to copy the features of some well-known commercial program, then we could have this as an option in the gimprc (but IMHO the default should be to promote the background layer automatically). -Raphael
Re: Is Add alpha channel really necessary?
May I make a humble suggestion. Change File-New to allow users to select a Fill Type of either Background w/o alpha Background w/ alpha Then users can select what they want to begin with. Flatten and Add Alpha Channel can still exist as is in the Layers menu. No automatic behind-the-scenes switching need be done. Power users have full control and newbies can simply select Background w/ alpha if they wish. Alan
Re: Is Add alpha channel really necessary?
[EMAIL PROTECTED] (Raphael Quinet) writes: On Tue, 16 May 2000, Jens Lautenbacher [EMAIL PROTECTED] wrote: I would say, simply make a layer by default have alpha always... I know I know it's more memory for that 0.001 % of cases where people start with one background layer and stick to one the whole time, without using alpha I still haven't found a good reason to keep the background layer "special" when the image contains multiple layers. If the only reasons are historical or to copy the features of some well-known commercial program, then we could have this as an option in the gimprc (but IMHO the default should be to promote the background layer automatically). One reason is the same as you gave for the single layer case: clearing means filling with a choosen background layer. So having a stack of layers with a dedicated background layer in a dedicated color makes sense, as clearing on the upper layers will clear to alpha, while it will clear to the background color on the background layer
Re: Is Add alpha channel really necessary?
On Tue, 16 May 2000, Jens Lautenbacher [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] (Raphael Quinet) writes: I still haven't found a good reason to keep the background layer "special" when the image contains multiple layers. If the only reasons are historical or to copy the features of some well-known commercial program, then we could have this as an option in the gimprc (but IMHO the default should be to promote the background layer automatically). One reason is the same as you gave for the single layer case: clearing means filling with a choosen background layer. So having a stack of layers with a dedicated background layer in a dedicated color makes sense, as clearing on the upper layers will clear to alpha, while it will clear to the background color on the background layer No, this is precisely what I consider to be counter-intuitive. IMHO, "clear with bg color" only makes sense if you do not understand or are not interested in the concepts of layers and transparency. So this can be good if you are mostly working with "flat" image formats. But if you start working with layers and transparency, then I would prefer to have a consistent behaviour for "clear": it should always make the selected area transparent, in all layers. If you really want "Edit-Clear" to reveal some color when you use it in the background layer of a multi-layered image, you always have the opportunity to add another layer below the one that was your background. This is probably easier to understand than having some special properties on one layer. (Anyway, in that case I would prefer to simply use "Edit-Fill with BG" or to drag the background color into the selection.) On Tue, 16 May 2000, Alan [EMAIL PROTECTED] wrote: May I make a humble suggestion. Change File-New to allow users to select a Fill Type of either Background w/o alpha Background w/ alpha Then users can select what they want to begin with. Flatten and Add Alpha Channel can still exist as is in the Layers menu. No automatic behind-the-scenes switching need be done. Power users have full control and newbies can simply select Background w/ alpha if they wish. This would not solve the most common problem which is: load an existing JPEG image, add a layer to it, then be confused because you cannot lower this layer below the background layer or because "Edit-Clear" and the Eraser tool behave differently on the two layers. Note that I definitely do not want to remove the "Flatten Image" option because it is very useful: as Carey Bunks said in a previous message, the user must be able to choose when and how an image is flattened before saving it. -Raphael
Re: Is Add alpha channel really necessary?
On Tue, May 16, 2000 at 05:42:54PM +0200, David Necas [EMAIL PROTECTED] wrote: NO, please. `Special' background layer maybe isn't very intuitive, but automatical promoting has the same problem: it's based on a side-effect and it's not gimp automatically promotes layers on a variety of occasions, without this being a problem so far. If an operation wasn't possible before and requires me to do an additional step (that doesn't loose data), I don't see a problem with making it automatic. If the user wants to raise the layer he should be able to do it. change a few pixels and try to save it and Gimp will start asking you about exporting, and flattening it. That's not anything I would call intuitive behaviour. Gimp should support trained users in the first place. If a user has no idea what flatten is, or which format supports alpha or not, then greying out menu entries that could confuse him is not particularly useful. The only principle problem is that code has to be written to support either way. -- -==- | ==-- _ | ---==---(_)__ __ __ Marc Lehmann +-- --==---/ / _ \/ // /\ \/ / [EMAIL PROTECTED] |e| -=/_/_//_/\_,_/ /_/\_\ XX11-RIPE --+ The choice of a GNU generation | |
