I'm developing an iPad application. I have been provided with a PNG image that contains some transparency - basically a drop shadow. The problem I'm having is that this is rendering poorly within the application, both on the device and in the sim.
I've made up some samples to illustrate. The first is how the image appears in the PSD (correctly that is). The second is how it appears on the device. You can see that the strip of shadow in the middle of the image is distinctly more yellow and poorly looking.
PDF http://www.aspyre.com.au/stackoverflow/photoshop.png On Device http://www.aspyre.com.au/stackoverflow/device.png
Any ideas what I'm doing wrong?
Edit: Links to files:
- PNG
- PSD
Edit 2: I've also tried pngcrush to remove the gamma, in case that was causing a problem, but no luck. Directions I followed were here: pngcrush
The reason you're getting a colour in your shadow is because the PSD's shadow layer is set to Multiply and has a colour in it. When you export it without a background, Photoshop is unable to multiply it to anything and just uses the layer as is. You need to grab the selection of the shadow layer, create a new layer, and fill that selection with black. Then set that new layer's opacity to something that mimics the old shadow.
Also I recommend you use Save-For-Web if you don't already. The colour-profile you use isn't much of an issue then as it will be stripped. However the point is valid that you want to be in sRGB when making iPhone/iPad graphics.
Link to your PSD adjusted: PSD
Common mistakes:
Your color space is non-standard. Either use no color space, or specify sRGB (strongly preferred).
You didn't save the PNG with gamma information included.
Without access to the actual files we're grasping at straws.. Maybe you have an 8-bit instead of 24-bit png?
For your shadow, use black instead of gray. Then adjust the transparency. That should fix it.
I had a similar issue that I resolved by disabling compression for an image. This is done in XCode by removing the .png extension. You can disable png compression for an entire project by editing the 'Compress PNG Files' project setting, but it is not recommended.
More details about Xcode PNG compression: http://iphonedevelopment.blogspot.com/2008/10/iphone-optimized-pngs.html
Related
Here is my site:
http://smartpeopletalkfast.co.uk/pp/
The 'Shop by Category' menu on the left is made of images and uses PNGs. The PNGs look fine at normal zoom but when I zoom out in FF and also on my Ipad white lines appear where the transparency begins.
I know PNGs can cause lots of headaches cross browser but this seems like a different issue. I havn't tested with other browsers.
Thanks
UPDATE - Does anyone know a link to a site where a PNG with transparency is shown over a background image or color? I want to see if this issue happens to other people in case its impossible to fix.
UPDATE2- I think this only happens on ipad and mac, but not pc.
UPDATE 3 - Here is a screen grab from firefox mac when Im zoomed out:
The problem is that your PNGs actually contain white.
Take a look at your PNG with its alpha channel removed
and compare it to this modified version with the alpha channel removed
Here is the modified version with alpha channel intact: - it looks the same as your file, but the transparent pixels are grey and transparent, not white and transparent. Try this version on your site and it should work.
To help you further, we'll need to know what software you are using to save the images. For example, in GIMP you have to make sure that you select "Save background color" when exporting the PNG, but other software may work differently.
I have a grayscale icon that I'm editing with Photoshop with a transparent background, but I can't, for the life of me, figure out how to convert the icon to one that can be used as an iPhone toolbar icon. If I simply save the image as a PNG, it doesn't show up as anti-aliased on the iPhone because every pixel with color is being rendered as black, instead of a shade of gray.
According to the Apple docs and other sources, there needs to be an alpha channel on the image to specify varying levels of transparency for each pixel. However, I have no idea what that means. I've read these posts and docs from Adobe and I still can't figure out how to properly convert a grayscale image into one that can be used as an iPhone toolbar icon. The blog post is hard to comprehend and poorly written, and the Adobe docs don't really help.
http://cahit.hayalet.net/blog/514/converting-an-image-to-iphone-toolbar-icon/
http://livedocs.adobe.com/en_US/Photoshop/10.0/help.html?content=WS74B356C9-353F-4483-8632-7B1A102F2A2E.html
Can someone point me in the right direction or provide exact, step-by-step directions to doing this in Photoshop?
It's much more simple than having to muck with actual masks in Photoshop.
iPhone toolbar icons are about 30px by 30px, so make a new Photoshop file with those dimensions. Ensure the background is transparent (you can specify that when creating a new file).
Then, any pixels you draw on top of this transparency become what iOS uses for the icon. Doesn't matter what color it is in Photoshop for NSToolbar icons -- they're automatically used as masks by iOS.
Leave transparent the parts you want to show through. Save as 24-bit PNG, and chuck into XCode as usual.
For a few icons that serve as good starting examples, check out the ones I publish for free here: http://glyphish.com Just take one of the PNGs and open it in Photoshop and you'll see that it's drawn in an arbitrary color (#444444) with varying levels of opacity to create darker and lighter parts of the icon.
This is more of a photoshop question than coding but anyway, here's a suggestion.
Lunacore has a good tutorial on how to use masks.
What you want to do is:
Make sure you're background is transparent.
Create a new layer and
fill it with any solid color.
Create a mask on the solid color
layer, and fill your greyscale image into the mask. (Use your
greyscale image as the mask.)
Toolbar icons use your image as a mask. They only consider what transparancy the image has. Not what color or shade.
I have a PNG file in a UIImageView, and next to that I have an EAGLView which displays the continuation of that same image (long story) as a texture, carved from the same original PNG. The point is, that these images, which should match up flawlessly, actually have somewhat differing color saturation.
Normally I'd blame my handling of the PNG texture load in GL, but when I hold Preview (with the PNG) up to the iPhone simulator, it's GL that's spot on, and the UIImageView that's wrong! It's taken the image and made it ever-so-slightly more saturated. The image view is opaque with 100% alpha.
I verified this on a clean UIImageView with another PNG file when put next to Preview.
Anyone know what's up?
If you are using Photoshop to save the png using the "Save for Web & Devices" tool, ensure the "Convert to sRGB" option is off and "Embed Color Profile" is also off. If you are using another editor, look for similar settings.
Read this, it will help explain better than I can.
I am about to submit my first app to the iTunes App Store. The docs say that the application needs to be submitted with a "512x512 px, 72ppi, RGB, flattened, no transparency JPEG image".
I have a couple of questions:
RGB - what exactly does it mean in this context.
Flattened - does it mean that if I am creating the image in Photoshop, I should flatten all the layers? Doesn't saving to JPEG kind of imply that? Or does it mean something completely different.
No transparency - JPEG doesn't support it to begin with. What color should the background be then?
RGB means to ensure that you save the image as an RGB (rather than CMYK) JPEG. This is very likely to be the case already. (You can change the colour mode via the 'Image -> Mode' menu in Photoshop if you have the icon in the CMYK colour space for some reason. That said, all images destined for on screen usage should remain with the RGB colour space.)
As you say, directly saving as a JPEG (or doing save for web) will flatten the layers for you.
Whatever colo(u)r you want it to be. (i.e: It'll appear as saved.)
Hope that makes sense.
They're just being very verbose. Just send the jpeg(saved for web) and all those conditions will be satisfied.
If you made a transparent background it will render as white on a jpeg anyway.
don't worry. send it :)
I’ve been busy working on the graphics for my iPhone application. I started working on generating icons for my UITabBar and ran into lots of problems. How do you create these icons?
I created this solution:
http://www.nailrails.com/?p=46
Are there any shortcomings to this approach? It seemed to work for the few icons I created...
Apple's guidelines can be found at http://developer.apple.com/library/ios/#documentation/UserExperience/Conceptual/MobileHIG/IconsImages/IconsImages.html#//apple_ref/doc/uid/TP40006556-CH14-SW1
The docs are pretty straightforward-- alpha is all that matters when the image gets loaded by the toolbar, meaning that anything that's not at least semitransparent will render in the same opaque shade. As for how I do that, I mainly use Adobe tools. Fireworks is my preferred tool but Photoshop's also more than up to it. Another one I've had good results with is Acorn, which is frankly a lot cheaper while being more than sophisticated enough for this kind of work. I'm not really a graphic designer but a certain familiarity with this kind of stuff goes with the job.
I have an article up on my site that shows how to use OmniGraffle with a template I use to create great iPhone toolbar icons in minutes:
http://steveweller.com/articles/toolbar-icons/
The template sets up a grid to work to that corresponds to one square for each pixel. You draw your icon in white on top of the black template background and then export as a PDF exactly the right area to match the icon size you need (typically 21 pixels high). Then you reimport the PDF, resize it to the final icon size (21 pixels again), and export as PNG. The template does nothing magical; it just provides an already set up working area and helps you get the final PNG right every time to the scale is correct.
You could use the same technique in Acorn or any other app that supports PDF export and layers.
(I use Gimp. Assume your icon layer already has alpha channel.)
Right click the layer, then add layer mask.
Done with option "transfer alpha channel of layer" chosen.
Select the whole layer (but not layer mask), and clear it with pure white.
Resize image to Apple-suggested size, and export it as png file.
You may also paint directly on the layer mask.