Al momento, stai seguendo questa domanda

Vedrai gli aggiornamenti nel tuofeed del contenuto seguito.
Potresti ricevere delle e-mail a seconda delle tuepreferenze per le comunicazioni.

what is image level

1 visualizzazione (ultimi 30 giorni)

Mostra commenti meno recenti

nadia il 30 Ott 2014

0
Link

Link diretto a questa domanda

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level

⋮

0
Link

Link diretto a questa domanda

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level

Commentato: Image Analyst il 31 Ott 2014

Risposta accettata: Image Analyst

hi i have some questions about image 's levels i should insert a watermark in 0 ,3 and 7 level of an image and calculate robustness against jpg, Gaussian noise attack but i do not know how to access these levels? is bitset function suitable for this? thanks

0 Commenti
Mostra -2 commenti meno recentiNascondi -2 commenti meno recenti

Accedi per commentare.

Accedi per rispondere a questa domanda.

Risposta accettata

Image Analyst il 30 Ott 2014

0
Link

Link diretto a questa risposta

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#answer_157150

⋮

0
Link

Link diretto a questa risposta

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#answer_157150

LSB_Watermarking.m

See attached demo where you can specify what bitplane to insert the hidden/watermark image.

12 Commenti
Mostra 10 commenti meno recentiNascondi 10 commenti meno recenti

nadia il 30 Ott 2014

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246666

⋮

Link

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246666

thanks Image Analyst but i have some question about this code: 1- what means this line bitToSet = str2double(cell2mat(inputdlg(prompt, dialogTitle, numberOfLines, defaultResponse))); 2- the prompt is used for bitplane for example if i want to hide the image in lsb i should enter 1 in the box or for level 3 i should enter 3 in the message box?

Image Analyst il 30 Ott 2014

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246667

⋮

Link

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246667

Apri in MATLAB Online

nadia's follow up question moved here:

Thanks Image Analyst but I have some questions about this code:

1- What does this line mean:

    bitToSet = str2double(cell2mat(inputdlg(prompt, dialogTitle, numberOfLines, defaultResponse)));

2- The prompt is used for bitplane. For example if I want to hide the image in lsb 1, should the user enter 1 in the box, or for level 3, the user should enter 3 in the message box?

Image Analyst il 30 Ott 2014

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246668

⋮

Link

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246668

1. I probably should have split it into 2 or 3 lines. Basically it gets a number as a double, because inputdlg returns a string. We want 3, not '3'.

2. Yes.

nadia il 30 Ott 2014

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246673

⋮

Link

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246673

thanks a lot for your answers if i want to check fidelity and robustness of my watermarking how can i use PSNR in matlab?

Image Analyst il 30 Ott 2014

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246690

⋮

Link

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246690

Apri in MATLAB Online

psnr.m

It's a built in function in the Image Processing Toolbox. Just look it up in the help:

peaksnr = psnr(A,ref) calculates the peak signal-to-noise ratio for the image A, with the image ref as the reference. A and ref must be of the same size and class.

If you don't have that toolbox, I have a manual method, attached.

nadia il 31 Ott 2014

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246756

⋮

Link

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246756

thank you very much

nadia il 31 Ott 2014

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246801

⋮

Link

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246801

Apri in MATLAB Online

hi i have an other question if i want to have jpeg attack on this watermark how can i do it? for example if wm was watermarked image i can do it with this code:

imwrite(wm,'wmjpg.jpg','jpeg','Quality',10)

if i want to calculate the correlation between watermark image and watermark image after attack how can i do it?

Image Analyst il 31 Ott 2014

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246808

⋮

Link

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246808

I guess you'd write it out very compressed, like you did. Then use imread() to read it back in. Then try to recover the watermark using your custom algorithm. Then have some kind of figure of merit as to how much you extracted resembles your original, expected, uncorrupted watermark. PSNR just compares images, which is not really what you're interested in, though it's a measure of how different the image is from your starting image to begin with. You should make up an ROC curve to determine how successful your algorithm is at finding the watermark.

nadia il 31 Ott 2014

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246822

⋮

Link

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246822

Apri in MATLAB Online

i have an other problem i produce a watermark image with rand function and round it now my watermark image is an zero-one image i should insert this watermark in lena image after i add Gaussian noise to final image and recover watermark from noisy watermark image it produce an error

Error using bitget
Inputs must be non-negative integers.

my noisy watermark image has values between 0-1 and every where its value is 1 it produce this error how can i solve this problem

Image Analyst il 31 Ott 2014

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246826

⋮

Link

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246826

Apri in MATLAB Online

It's not much of a watermark if it was created with the rand() function. Watermarks have structure as far as I know, and to determine if your image was "stolen" you have to retrieve the watermark and determine if the structure is still there. There may be some fancier ones that watermark with other things than images. I saw one that used the Fibonacci series that was very robust to cropping, noise, etc.

Anyway, you need to multiply your image by 255 and then cast to uint8

grayImage = uint8(255 * normalizedImage);

nadia il 31 Ott 2014

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246864

⋮

Link

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246864

if i want to insert watermark in DCT of image how can i do it?

Image Analyst il 31 Ott 2014

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246898

⋮

Link

Link diretto a questo commento

https://it.mathworks.com/matlabcentral/answers/160717-what-is-image-level#comment_246898

I don't know. I'd have to research it because it's not my field. But I'll let you do that since it's your problem. Good luck.

Accedi per commentare.

Più risposte (0)

Accedi per rispondere a questa domanda.

Vedere anche

Categorie

Image Processing and Computer Vision Image Processing Toolbox Image Filtering and Enhancement Watermarking

Scopri di più su Watermarking in Help Center e File Exchange

Prodotti

Image Processing Toolbox

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Si è verificato un errore

Impossibile completare l'azione a causa delle modifiche apportate alla pagina. Ricarica la pagina per vedere lo stato aggiornato.

Translated by

Seleziona un sito web

Seleziona un sito web per visualizzare contenuto tradotto dove disponibile e vedere eventi e offerte locali. In base alla tua area geografica, ti consigliamo di selezionare: .

(English)
(Deutsch)
(Français)

（简体中文）
(English)

Puoi anche selezionare un sito web dal seguente elenco:

Come ottenere le migliori prestazioni del sito

Per ottenere le migliori prestazioni del sito, seleziona il sito cinese (in cinese o in inglese). I siti MathWorks per gli altri paesi non sono ottimizzati per essere visitati dalla tua area geografica.

Americhe

América Latina (Español)
Canada (English)
United States (English)

Europa

Belgium (English)
Denmark (English)
Deutschland (Deutsch)
España (Español)
Finland (English)
France (Français)
Ireland (English)
Italia (Italiano)
Luxembourg (English)

Netherlands (English)
Norway (English)
Österreich (Deutsch)
Portugal (English)
Sweden (English)
Switzerland
United Kingdom (English)

Asia-Pacifico

Australia (English)
India (English)
New Zealand (English)
中国
- 简体中文Chinese
- English
日本Japanese (日本語)
한국Korean (한국어)

Contatta l’ufficio locale

what is image level

0 Commenti Mostra -2 commenti meno recentiNascondi -2 commenti meno recenti

Risposta accettata

12 Commenti Mostra 10 commenti meno recentiNascondi 10 commenti meno recenti

Più risposte (0)

Vedere anche

Categorie

Tag

Prodotti

Community Treasure Hunt

0 Commenti
Mostra -2 commenti meno recentiNascondi -2 commenti meno recenti

12 Commenti
Mostra 10 commenti meno recentiNascondi 10 commenti meno recenti