Image getting blured in iphone and not in ipod

smsawant · 04-23-2009, 10:50 PM

hi,

i am sending image from myapplication.
when i send it through ipod it is getting send as it is.
but when i send it through iphone it is getting blurred

i am using .jpg image of dimensions 320*460

plz kindly help me if anyone have idea about it.

thanks in advance.

jtara · 04-24-2009, 01:01 AM

You could start by telling us what file format, size, etc.

smsawant · 04-24-2009, 01:54 AM

Quote:

Originally Posted by jtara

You could start by telling us what file format, size, etc.

i am using .jpg image of dimensions 320*460

Negativi · 04-24-2009, 04:19 AM

Help please!

funkytaco · 04-24-2009, 11:54 AM

By blurred, do you mean sent in a lower quality?

wdn · 04-24-2009, 12:22 PM

Is the status bar hidden on the iPhone for some reason? It may be trying to scale the image from 460 to 480 pixels. Also make sure you round your rects to integral values to avoid fuzzy images.

smsawant · 04-25-2009, 11:40 AM

Quote:

Originally Posted by funkytaco

By blurred, do you mean sent in a lower quality?

i m taking screenshot of image and then send it.
image is getting blur when i send it through iphone
but when i send it through ipod - touch
image is ok.

plz reply if anyone got a same problem.

jtara · 04-25-2009, 01:36 PM

My screenshots are clear.

You need to be more clear and specific if you want to get help here. "It doesn't work" isn't going to get you much useful response. I still do not know just what you are doing. You said you are sending an image from your application. Then you said you are taking a screen shot. Which is it?

Have you examined the images your received? What pixel dimensions are they? How many bytes are they? Look at them in an image editor, view properties and see what is different. Zoom in and try to identify what is wrong. If the issue is JPEG compression, you should be able to identify the JPEG artifacts and see how they are different in the two cases.

If you need screenshots for the app store or your web site, this is a case of "doctor, doctor":

Patient: "Doctor, doctor, it hurts when I do this!"

Doctor: "So, stop doing that!"

Take your screen shots on the iPod Touch. Problem solved.

Better yet, take them in Organizer, because they will then be PNGs. You really don't want to be using JPEGs for the app store.

One possibility might be that image quality settings differ between the two devices, but I don't see any settings for that. Then again, you also don't say what version of the OS you are using. Perhaps you are running 3.0, and there are settings for screenshot JPEG quality in 3.0?

ambiensignal · 04-25-2009, 03:04 PM

Quote:

Originally Posted by jtara

You really don't want to be using JPEGs for the app store.

Actually, the App Store only accepts JPEGs or TIFFs, and not PNGs.

jtara · 04-25-2009, 03:52 PM

Quote:

Originally Posted by ambiensignal

Actually, the App Store only accepts JPEGs or TIFFs, and not PNGs.

You can convert the PNGs to TIFFs, without loss.

JPEG is lossy, and will have nasty artifacts. It doesn't make sense to convert a JPG to a TIFF.

So, start with a PNG, which has only lossless compression, and convert to TIFF, which is also lossless.

ambiensignal · 04-25-2009, 04:12 PM

Quote:

Originally Posted by jtara

You can convert the PNGs to TIFFs, without loss.

JPEG is lossy, and will have nasty artifacts. It doesn't make sense to convert a JPG to a TIFF.

So, start with a PNG, which has only lossless compression, and convert to TIFF, which is also lossless.

...you can submit the JPG, no conversion needed.

jtara · 04-25-2009, 04:35 PM

Quote:

...you can submit the JPG, no conversion needed.

You CAN, but it's better if you don't. Why send an inferior image?

Apple may resize/convert for the App Store. They may change their mind about size/format in the future. Give them a full, lossless image to work with. You are going to lose quality starting with lossy compression like JPEG.

Take a screenshot on the iPhone and email it to yourself. Take a screenshot with Organizer. Zoom in on each one. Which one do you want to send to Apple?

ambiensignal · 04-25-2009, 08:34 PM

Quote:

Originally Posted by jtara

You CAN, but it's better if you don't. Why send an inferior image?

Okay, there's something you clearly don't understand.
You take a picture, starting in JPEG (an "inferior image").
You take a picture, starting in PNG, then convert it to JPEG (an "inferior image").

Same thing.

No one cares if PNG has lossless compression because you aren't sending that to Apple. You're sending the "converted version", which would give you a JPEG representation, which, according to you, has lossy compression. Or you send the JPEG representation, which according to you, has lossy compression.

You're sending lossy compression either way.

Quote:

Originally Posted by jtara

Give them a full, lossless image to work with. ... Take a screenshot on the iPhone and email it to yourself. Take a screenshot with Organizer. Zoom in on each one. Which one do you want to send to Apple?

Oh, definitely I'd send the PNG, it's much better and we can all agree on that. TOO BAD YOU CAN'T SEND THAT VERSION TO APPLE.

jtara · 04-25-2009, 09:20 PM

Quote:

No one cares if PNG has lossless compression because you aren't sending that to Apple. You're sending the "converted version", which would give you a JPEG representation

Maybe YOU are sending them JPEG. I am sending the TIFF. They take either JPEG or TIFF.

TIFF is lossless. You're conveniently skipping over that part.

I reiterate: since they take two formats, one lossy, one lossless, why on earth would you send them the lossy format, given a choice? Since we do have a choice, I'll send them the lossless version, thank you!

ambiensignal · 04-25-2009, 09:26 PM

Oops, I just checked iTunes Connect. They seem to take PNG's now too. Wasn't there before

**meowmix23F** · 04-25-2009, 10:03 PM

Since the ipod uses wifi, the image isn't compressed. Otherwise, when you send data, the iPhone automatically compresses it to optimize speed. It's annoying. Try zipping the file, sending it, and then unzipping it on the server side.

jtara · 04-25-2009, 11:32 PM

Quote:

Since the ipod uses wifi, the image isn't compressed. Otherwise, when you send data, the iPhone automatically compresses it to optimize speed

Aha! Mystery solved!

It's interesting that the iPhone doesn't send it uncompressed when on WiFi. I know this to be the case, because I sent myself a test screenshot while on WiFi. I wasn't really thinking about WiFi as a factor at the time, though. (Unless it just uses different levels of JPEG compression? I am assuming the Touch sends PNG, and the iPhone sends JPEG? I don't have a Touch, so dunno.)

I assume the OP is just taking a screenshot by pressing the home and wake buttons, so he doesn't have the option of Zipping it. Or can an app take a screenshot?

I don't think zipping it will help with size. (The OP wasn't complaining about size, anyway - just the difference in quality between the two devices.) The PNG is already losslessly compressed, and it uses an algorithm optimized for images. I doubt that Zip would compress it further. If anything, it is likely to grow ever so slightly.

**meowmix23F** · 04-25-2009, 11:39 PM

Zipping it and unzipping it is so that the iphone is tricked into thinking your data *isnt* an image, when in fact it is, so that it doesn't compress it for you (and therefore lessen the quality of the image)

jtara · 04-26-2009, 04:34 AM

Quote:

Originally Posted by meowmix23F

Zipping it and unzipping it is so that the iphone is tricked into thinking your data *isnt* an image, when in fact it is, so that it doesn't compress it for you (and therefore lessen the quality of the image)

I wouldn't think that it's compressed during transmission, but when it's taken.

And, again, if we are talking about screen shots taken by pressing home and wake, (or whatever the button on top is called...), your app has no control over that anyway - there's no way you could zip it.

I'd be VERY surprised if it would change any data that an application sends.