The depiction of Gods is not accurate these days. See my question about Brahma depicted as old here.
What was the actual colour of Rama and Krishna?
In Sundara Kanda of Valmiki Ramayana Sita asks Hanuman to prove himself that he knew Rama and Lakshmana. Then Hanuman starts describing various characteristics Of Rama. As a part of the description, Hanuman says as follows:
दुन्दुभि स्वन निर्घोषः स्निग्ध वर्णः प्रतापवान् |
समः सम विभक्त अन्गो वर्णम् श्यामम् समाश्रितः ||
He has a voice like the sound of a kettle-drum. He has a shining skin. He is full of splendour. He is square-built. His limbs are built symmetrically. He is endowed with a dark-brown1 complexion.
When Sita enters the fire by herself, All the Gods reach Lanka and approach Rama. Brahma describes who Rama in reality is and proclaims his(Rama's) divinity.
सीता लक्ष्मीर्भवान् विष्णुर्देवः कृष्णः प्रजापतिः ||
वधार्थं रावणस्येह प्रविष्टो मानुषीं तनुम् |
sītā lakṣmīrbhavān viṣṇurdevaḥ kṛṣṇaḥ prajāpatiḥ ||
vadhārthaṃ rāvaṇasyeha praviṣṭo mānuṣīṃ tanum |
Seetha is no other than Goddess Lakshmi (the divine consort of Lord Vishnu), while you are Lord Vishnu. You are having a shining dark-blue hue. You are the Lord of created beings. For the destruction of Ravana, you entered a human body here, on this earth.
Ramaraksha stotram written by Budha Kaushika muni is a popular hymn. In that stotra, Budha Kaushika rushi praises Lord Rama as below.
ध्यात्वा नीलोत्पलश्यामं रामं राजीवलोचनम् ।
जानकीलक्ष्मणोपेतं जटामुकुटमंडितम् ||
dhyātvā nīlotpalaśyāmaṃ rāmaṃ rājīvalocanam ।
jānakīlakṣmaṇopetaṃ jaṭāmukuṭamaṃḍitam ||
Meditating on Rama who is black like the blue lotus flower, Who has lotus like eyes, who is our Lord, Who is accompanied by Sita and Lakshmana,
Whose head is surrounded by the tufted hair.
राजेंद्रं सत्यसंधं दशरथतनयं श्यामलं शांतमूर्तिम् ।
rājeṃdraṃ satyasaṃdhaṃ daśarathatanayaṃ śyāmalaṃ śāṃtamurtiṃ |
Who is the best among kings, Who is truthful, who is son of Dasaratha, Who is black and Who is the personification of peace and patience.
So, the pictures you have seen Rama in gowra(pale red,white, yellow) varna are artistic imaginations. Actually He was in the colour of a lotus. He is also called Nīlimeghaśyāma meaning
the one who is in the complexion of a blue cloud.
When it comes to Sri Krishna, He is not black. His complexion is like complexion of a dark blue cloud. The aura behind Rama or Krishna or any other God represents the divinity in them.
Lord Rama and Lord Krishna were not red or not completely black. They were in a complexion of a blue lotus just like the Lord Srimannarayana.
The dhyaanam of Sri Vishnu sahasranamam describes Sri MahaVishnu as follows:
शान्ताकारं भुजगशयनं पद्मनाभं सुरेशम्
विश्वाधारम् गगन सदृशं मेघवर्णं शुभाङ्गम् |
ṣānthakaram Bhujaga ṣayanam Padmānabham ṣuresam
Visvādhāram gagana sadrusam ṃegha Varnam ṣubāngam||
We meditate upon Vishnu, who is ever peaceful, who lies on the great serpent-bed from whose navel springs the lotus of the creative power, who is the controller of the gods, whose form is the entire universe , and who is the foundation for the universe, who is all pervading as the sky, of the hue of the cloud, of fascinating beauty.
मेघश्यामं पीतकौशेयवासं श्रीवत्साङ्कं कौस्तुभोद्भासिताङ्गम्
meghaśyāmaṃ pītakauśeyavāsaṃ śrīvatsāṅkaṃ kaustubhodbhāsitāṅgam |
Whose body is of the dark like the clouds. He lives in the pure ocean of milk. He has Lakshmi in his chest.
From the above verses, it is clear that the complexion of Rama and Krishna is just as the complexion of Lord Srimannarayana. It is because, they were the incarnations of the Lord Vishnu.
1.Here the word shyama has many meanings like black,brown,blue, dark green etc., Among those words, the translator of the verse chose dark- brown.But from below instances we shall know the complexion of bluish-black.